Mega counties, 1892-2020

These are the counties that have cast the most vote in US presidential elections. 

In The Great Revolt, Salena Zito and Brad Todd wrote that 

Of the forty-four mega counties in the nation with populations over one million, Trump carried only three--[Tarrant County, Texas, Maricopa County, Arizona, and Suffolk County, New York]. 

The forty-four most vote-casting counties in the 2016 election were slightly different, which is not surprising. Of the forty-four most vote-casting counties in the 2016 election, Trump carried five: Maricopa, Suffolk [NY], Tarrant, Pinellas, and Duval [FL], with Duval being #44. 

Forty-two counties cast more than 1/3 of 1% of the national popular vote in 2016. These, again, include Pinellas, which was not one of Zito's mega counties. However, this gives us a list of counties that gives us roughly the same number as Zito's mega counties. In general, this likely means that the overlap between these forty-two, and Zito's forty-four, is high, and that this list of counties mostly captures Zito's concept. I don't have access to historical county population data, and number of votes cast has been used as a metric that roughly captures a county's demographic size (e.g., by OZY, and by Dante Chinni). Hence, I will be using 'mega county' to refer to counties that cast at least 1/3 of 1% of the national vote in a given election.

Zito compares Trump's performance in the mega counties with Romney's in 2012. I don't know if she goes further back, but if we want to be able to compare performances in the mega counties across very temporally disparate elections, it would do to define mega counties as ones casting a certain proportion of the national vote (or comprising a certain proportion of the national population), rather than as those that cast a certain absolute number of votes (or have a certain absolute population), or that are the top n counties in terms of votes cast or population, where n is a fixed number. (These are the approaches of Zito and Chinni, respectively.) 

Furthermore, if the number of counties we're looking at is small (as is the case with Chinni), it may tell us something misleading--for example, from looking at how the ten most vote-casting counties voted in 1996 (Clinton carried six), Chinni concluded that Clinton did well in 'urban communities' (but that Hillary Clinton did better, carrying nine of ten in 2016). Leaving aside the aptness of his characterising these counties as 'urban communities' (in 2020, Chuck Todd referred to Maricopa as 'arguably the largest suburb in America'), if we do the same comparison with 1976, we find that--in a close election--Carter also carried six of the ten most vote-casting counties, which would seem to imply that Bill Clinton did worse in 'urban communities' (relative to his national performance) than Carter did in 1976.

As it happens, the number of mega counties is relatively consistent from the 1940s on (which makes comparison between temporally distant elections easier). For 1916, I added the counties that cast between 1/4 and 1/3 of 1% of the national vote, and for 1896, I added the counties that cast between 1/5 and 1/4 of 1% as well, to make the lists more numerically comparable with more recent lists. (However, in my discussion, I don't count these additional counties as 'mega counties'.) These counties are demarcated from the actual mega counties by a line. (I also added the counties that cast between 1/4 and 1/3 of 1% of the national vote for a few other elections in that general period, before deciding I didn't want to generalise this across that period, but since I had gathered the information, I thought I might as well leave it in for those elections.)

We start in 1892 because before this election, we don't have data for Illinois, Maryland, Minnesota, Indiana, and Wisconsin. (In addition, we don't have data for New Jersey before 1896.)

The bolded counties are the counties that gave their respective parties their largest raw vote margins. If one of these counties doesn't show up, it will be listed after an elipsis. 

2020 (Threshold: 527,944.67)
Los Angeles, CA: 4,264,365
Cook, IL: 2,321,399
Maricopa, AZ: 2,076,086
Harris, TX: 1,640,818
San Diego, CA: 1,602,143
Orange, CA: 1,522,113
King, WA: 1,210,507
Dade, FL: 1,156,816
Riverside, CA: 997,156
Clark, NV: 972,510
Broward, FL: 957,672
Dallas, TX: 919,504
Brooklyn, NY: 913,690
Wayne, MI: 874,018
Middlesex, MA: 869,347
Santa Clara, CA: 850,741
San Bernardino, CA: 841,130
Tarrant, TX: 834,697
Queens, NY: 788,262
Alameda, CA: 773,753
Palm Beach, FL: 773,158
Oakland, MI: 771,991
Suffolk, NY: 771,751
Bexar, TX: 770,818
Hennepin, MN: 755,969
Philadelphia, PA: 741,377
Nassau, NY: 730,983
Allegheny, PA: 719,733
Sacramento, CA: 718,440
Hillsborough, FL: 712,063
Manhattan, NY: 695,263
Orange, FL: 647,403
Franklin, OH: 632,532
Wake, NC: 631,830
Cuyahoga, OH: 627,160
Travis, TX: 608,575
Fairfax, VA: 600,823
Contra Costa, CA: 581,316
Mecklenburg, NC: 567,053
Pinellas, FL: 559,715
St Louis County, MO: 545,248
Salt Lake, UT: 541,175
Montgomery, MD: 533,743
...
Montgomery, TX: 271,543

(43 counties; Trump carried one)

2016 (Threshold: 455,564.25)
Los Angeles, CA: 3,434,308
Cook, IL: 2,158,576
Maricopa, AZ: 1,608,875
Harris, TX: 1,312,112
San Diego, CA: 1,306,400
Orange, CA: 1,197,521
King, WA: 998,499
Dade, FL: 980,204
Broward, FL: 831,951
Brooklyn, NY: 801,054
Middlesex, MA: 796,735
Wayne, MI: 777,838
Clark, NV: 767,156
Dallas, TX: 758,973
Riverside, CA: 751,391
Philadelphia, PA: 707,631
Santa Clara, CA: 703,709
Queens, NY: 683,483
Hennepin, MN: 679,970
Suffolk, NY: 677,151
Tarrant, TX: 668,514
Oakland, MI: 664,614
Manhattan, NY: 663,843
Palm Beach, FL: 662,332
Alameda, CA: 654,266
San Bernardino, CA: 653,983
Allegheny, PA: 650,114
Nassau, NY: 642,933
Cuyahoga, OH: 608,879
Hillsborough, FL: 597,660
Bexar, TX: 589,645
Franklin, OH: 587,524
Sacramento, CA: 559,330
Fairfax, VA: 551,183
Orange, FL: 546,275
Wake, NC: 527,624
St Louis County, MO: 514,858
Pinellas, FL: 492,403
Montgomery, MD: 478,873
Mecklenburg, NC: 472,857
Travis, TX: 468,720
Contra Costa, CA: 466,175
...
Montgomery, TX: 204,632

(42 counties; Trump carried four)

2012 (Threshold: 430,284.7)
Los Angeles, CA: 3,181,067
Cook, IL: 2,011,598
Maricopa, AZ: 1,376,543
San Diego, CA: 1,192,282
Harris, TX: 1,188,585
Orange, CA: 1,122,664
King, WA: 967,154
Dade, FL: 878,314
Wayne, MI: 815,825
Broward, FL: 756,422
Middlesex, MA: 754,170
Brooklyn, NY: 736,982
Dallas, TX: 710,117
Clark, NV: 691,190
Philadelphia, PA: 690,327
Hennepin, MN: 680,059
Riverside, CA: 661,907
Oakland, MI: 651,607
Cuyahoga, OH: 645,262
Santa Clara, CA: 643,091
Allegheny, PA: 622,081
Tarrant, TX: 610,890
Palm Beach, FL: 600,721
Manhattan, NY: 600,291
Alameda, CA: 595,642
Queens, NY: 595,245
Suffolk, NY: 594,266
San Bernardino, CA: 581,517
Franklin, OH: 572,188
Nassau, NY: 568,151
Hillsborough, FL: 542,102
Fairfax, VA: 529,287
St Louis County, MO: 528,676
Sacramento, CA: 516,809
Bexar, TX: 513,681
Milwaukee, WI: 492,576
Wake, NC: 486,427
Orange, FL: 466,359
Pinellas, FL: 457,702
Montgomery, MD: 455,992
Mecklenburg, NC: 448,900
Contra Costa, CA: 438,226

(42 counties; Romney carried three)

2008 (Threshold: 437,712.7)
Los Angeles, CA: 3,316,630
Cook, IL: 2,137,466
Maricopa, AZ: 1,380,571
San Diego, CA: 1,235,503
Harris, TX: 1,171,472
Orange, CA: 1,153,687
King, WA: 922,032
Wayne, MI: 890,326
Dade, FL: 864,636
Brooklyn, NY: 759,848
Dallas, TX: 738,463
Broward, FL: 735,091
Middlesex, MA: 726,031
Philadelphia, PA: 717,329
Manhattan, NY: 667,895
Cuyahoga, OH: 667,299
Santa Clara, CA: 664,535
Hennepin, MN: 663,780
Suffolk, NY: 659,403
Oakland, MI: 659,068 
Allegheny, PA: 651,436
Clark, NV: 651,142
Riverside, CA: 646,274
Queens, NY: 639,989
Nassau, NY: 635,482
Tarrant, TX: 628,553
Alameda, CA: 621,029
San Bernardino, CA: 606,334
Palm Beach, FL: 591,436
Franklin, OH: 561,763
St Louis County, MO: 559,854
Sacramento, CA: 542,859
Bexar, TX: 525,715
Fairfax, VA: 516,254
Hillsborough, FL: 514,501
Milwaukee, WI: 475,192
Pinellas, FL: 465,152
Orange, FL: 463,039
Contra Costa, CA: 453,244
Erie, NY: 441,985
Montgomery, MD: 439,261

(41 counties; McCain carried three)

2004 (Threshold: 407,651.15)
Los Angeles, CA: 3,023,280
Cook, IL: 2,049,434
Maricopa, AZ: 1,192,751
San Diego, CA: 1,134,848
Orange, CA: 1,075,399
Harris, TX: 1,067,968
King, WA: 893,534
Wayne, MI: 864,728
Dade, FL: 774,726
Broward, FL: 706,872
Middlesex, MA: 688,960
Brooklyn, NY: 687,780
Dallas, TX: 687,709
Philadelphia, PA: 674,069
Cuyahoga, OH: 673,777
Hennepin, MN: 646,981
Allegheny, PA: 645,069
Oakland, MI: 641,977
Manhattan, NY: 641,747
Suffolk, NY: 638,712
Nassau, NY: 618,343
Queens, NY: 605,062
Santa Clara, CA: 603,816
Alameda, CA: 562,086
Tarrant, TX: 560,141
Riverside, CA: 557,579
Clark, NV: 545,397
Palm Beach, FL: 544,622
St Louis County, MO: 542,983
Franklin, OH: 525,827
San Bernardino, CA: 522,777
Milwaukee, WI: 482,236
Sacramento, CA: 477,866
Bexar, TX: 475,314
Hillsborough, FL: 463,222
Fairfax, VA: 461,379
Pinellas, FL: 455,357
Erie, NY: 445,138
Hamilton, OH: 424,025
Montgomery, MD: 415,225
Contra Costa, CA: 413,028

(41 counties; George W. Bush carried 12) 

2000 (Threshold: 351,404.74)
Los Angeles, CA: 2,695,154
Cook, IL: 1,865,907
Harris, TX: 974,822
Orange, CA: 970,905
San Diego, CA: 958,634
Maricopa, AZ: 899,808
King, WA: 794,196
Wayne, MI: 768,627
Middlesex, MA: 657,048
Dade, FL: 625,552
Brooklyn, NY: 617,105
Dallas, TX: 613,039
Nassau, NY: 589,707
Allegheny, PA: 582,478
Cuyahoga, OH: 574,782
Suffolk, NY: 573,866
Hennepin, MN: 573,846
Oakland, MI: 570,265
Manhattan, NY: 563,232
Philadelphia, PA: 561,180
Queens, NY: 555,930
Broward, FL: 525,239
Santa Clara, CA: 548,129
Alameda, CA: 494,336
St Louis County, MO: 486,884
Tarrant, TX: 472,389
San Bernardino, CA: 454,893
Riverside, CA: 451,127
Milwaukee, WI: 433,537
Palm Beach, FL: 433,222
Sacramento, CA: 431,550
Erie, NY: 424,654
Franklin, OH: 414,074
Fairfax, VA: 413,775
Bexar, TX: 412,726
Pinellas, FL: 398,526
Clark, NV: 382,198
Contra Costa, CA: 381,478
Hamilton, OH: 377,899
Westchester, NY: 371,775
Montgomery, MD: 371,688
Fairfield, CT: 370,289
Hartford, CT: 367,556
Bergen, NJ: 366,721
DuPage, IL: 364,362
Hillsborough, FL: 360,354

(46 counties; George W. Bush carried 13)

1996 (Threshold: 320,925.45)
Los Angeles, CA: 2,411,014
Cook, IL: 1,716,586
San Diego, CA: 884,151
Orange, CA: 864,576
Harris, TX: 855,893
Maricopa, AZ: 817,432
King,WA: 741,104
Wayne, MI: 731,597
Middlesex, MA: 627,977
Cuyahoga, OH: 561,892
Dallas, TX: 555,953
Dade, FL: 553,782
Nassau, NY: 544,664
Brooklyn, NY: 539,833
Allegheny, PA: 538,615
Philadelphia, PA: 533,277
Hennepin, MN: 524,306
Santa Clara, CA: 523,291
Queens, NY: 511,296
Oakland, MI: 505,642
Suffolk, NY: 505,213
Broward, FL: 505,098
Manhattan, NY: 492,899
St Louis County, MO: 462,278
Alameda, CA: 462,044
San Bernardino, CA: 413,355
Erie, NY: 410,234
Tarrant, TX: 409,644
Sacramento, CA: 407,414
Franklin, OH: 400,515
Palm Beach, FL: 397,354
Riverside, CA: 391,613
Pinellas, FL: 376,272
Hamilton, OH: 372,068
Milwaukee, WI: 371,380
Fairfax, VA: 365,263
Bergen, NJ: 362,887
Bexar, TX: 362,489
Hartford, CT: 356,841
Contra Costa, CA: 352,602
Fairfield, CT: 352,227
Westchester, NY: 344,863
Montgomery, MD: 334,897
Shelby, TN: 326,380
New Haven, CT: 325,891
DuPage, IL: 322,688

(46 counties; Dole carried 10)

1992 (Threshold: 348,079.74)
Los Angeles, CA: 2,753,403
Cook, IL: 2,146,655
San Diego, CA: 986,646
Orange, CA: 972,549
Harris, TX: 942,947
Maricopa, AZ: 876,832
Wayne, MI: 841,965
King, WA: 778,593
Middlesex, MA: 689,453
Dallas, TX: 661,252
Cuyahoga, OH: 640,241
Philadelphia, PA: 638,058
Allegheny, PA: 614,187
Nassau, NY: 609,326
Santa Clara, CA: 602,055
Hennepin, MN: 586,619
Brooklyn, NY: 581,594
Suffolk, NY: 567,955
Queens, NY: 555,956
Oakland, MI: 555,760
Dade, FL: 544,843
St Louis County, MO: 534,763
Broward, FL: 533,050
Manhattan, NY: 531,673
Alameda, CA: 530,145
San Bernardino, CA: 474,070
Tarrant, TX: 471,396
Milwaukee, WI: 465,496
Sacramento, CA: 453,512
Erie, NY: 451,496
Franklin, OH: 444,801
Riverside, CA: 430,275
Pinellas, FL: 422,851
Bexar, TX: 415,276
Hartford, CT: 414,804
Fairfield, CT: 409,410
Palm Beach, FL: 405,251
Hamilton, OH: 403,420
Bergen, NJ: 403,137
Fairfax, VA: 385,218
New Haven, CT: 385,132
Contra Costa, CA: 382,823
Westchester, NY: 378,840
DuPage, IL: 370,987
Shelby, TN: 366,110
Montgomery, MD: 362,613
Macomb, MI: 349,238

(47 counties; George H. W. Bush carried 14)

1988 (Threshold: 305,315.62)
Los Angeles, CA: 2,644,671
Cook, IL: 2,026,144
San Diego, CA: 869,195
Orange, CA: 865,307
Harris, TX: 814,160
Wayne, MI: 748,156
Maricopa, AZ: 681,508
Philadelphia, PA: 674,977
Middlesex, MA: 662,628
King, WA: 648,957
Cuyahoga, OH: 601,117
Dallas, TX: 594,538
Nassau, NY: 592,418
Allegheny, PA: 586,151
Brooklyn, NY: 549,019
Queens, NY: 546,729
Santa Clara, CA: 541,528
Hennepin, MN: 538,562
Suffolk, NY: 514,350
Manhattan, NY: 506,551
Dade, FL: 490,265
St Louis County, MO: 480,676
Alameda, CA: 478,997
Oakland, MI: 462,488
Broward, FL: 440,605
Milwaukee, WI: 439,545
Erie, NY: 430,792
Tarrant, TX: 396,237
Sacramento, CA: 395,690
San Bernardino, CA: 392,008
Bergen, NJ: 389,933
Franklin, OH: 377,357
Hartford, CT: 376,536
Fairfield, CT: 374,878
Westchester, NY: 371,008
Hamilton, OH: 370,384
Bexar, TX: 369,749
Pinellas, FL: 365,370
New Haven, CT: 342,361
Riverside, CA: 336,348
Contra Costa, CA: 331,511
Fairfax, VA: 328,365
Palm Beach, FL: 327,217
Montgomery, MD: 320,896
Marion, IN: 315,095
Norfolk, MA: 315,056
DuPage, IL: 314,054
Monroe, NY: 311,466
Shelby, TN: 308,988
Essex, MA: 305,500

(50 counties; George H. W. Bush carried 29)

1984 (Threshold: 308,844.1)
Los Angeles, CA: 2,630,090
Cook, IL: 2,180,735
Harris, TX: 872,167
Wayne, MI: 868,343
Orange, CA: 854,108
San Diego, CA: 774,756
Philadelphia, PA: 772,102
Allegheny, PA: 665,748
Cuyahoga, OH: 651,633
Middlesex, MA: 646,754
King, WA: 639,261
Nassau, NY: 634,063
Queens, NY: 615,578
Dallas, TX: 610,496
Brooklyn, NY: 600,771
Maricopa, AZ: 572,273
Dade, FL: 548,312
Santa Clara, CA: 530,910
Hennepin, MN: 529,234
Manhattan, NY: 526,671
Suffolk, NY: 508,056
Alameda, CA: 484,742
St Louis County, MO: 480,828
Erie, NY: 461,671
Oakland, MI: 458,800
Milwaukee, WI: 458,017
Broward, FL: 449,226
Bergen, NJ: 424,718
Fairfield, CT: 391,179
Franklin, OH: 390,474
Westchester, NY: 390,308
Hamilton, OH: 388,815
Hartford, CT: 378,405
Sacramento, CA: 371,936
Pinellas, FL: 369,249
Tarrant, TX: 368,862
New Haven, CT: 354,712
San Bernardino, CA: 345,504
Bexar, TX: 340,826
Shelby, TN: 337,302
The Bronx, NY: 333,683
Contra Costa, CA: 317,878
Marion, IN: 317,148
Monroe, NY: 316,277
Essex, NJ: 314,543

(45 counties; Mondale carried 15)

1980 (Threshold: 288,365.6)
Los Angeles, CA: 2,440,185
Cook, IL: 2,163,097
Wayne, MI: 893,977
Orange, CA: 780,212
Harris, TX: 720,014
Philadelphia, PA: 718,100
San Diego, CA: 716,866
Middlesex, MA: 637,679
Allegheny, PA: 621,418
Cuyahoga, OH: 614,682
King, WA: 600,157
Nassau, NY: 596,154
Queens, NY: 560,923
Dade, FL: 524,905
Brooklyn, NY: 521,109
Dallas, TX: 518,213
Hennepin, MN: 505,372
Maricopa, AZ: 486,834
St Louis County, MO: 485,105
Santa Clara, CA: 477,003
Oakland, MI: 465,038
Milwaukee, WI: 464,008
Suffolk, NY: 449,655
Manhattan, NY: 441,901
Erie, NY: 420,473
Alameda, CA: 417,617
Bergen, NJ: 415,157
Broward, FL: 410,561
Franklin, OH: 373,045
Hartford, CT: 371,380
Fairfield, CT: 368,098
Westchester, NY: 365,166
Hamilton, OH: 358,541
Pinellas, FL: 345,003
New Haven, CT: 337,732
Sacramento, CA: 322,120
Marion, IN: 314,269
Shelby, TN: 308,517
Bexar, TX: 308,474
Monroe, NY: 306,733
Tarrant, TX: 305,066
Norfolk, MA: 303,729
Macomb, MI: 297,905
Essex, MA: 297,533
San Bernardino, CA: 289,812

(45 counties; Carter carried 16)

1976 (Threshold: 271,771.95)
Los Angeles, CA: 2,459,077
Cook, IL: 2,209,748
Wayne, MI: 912,990
Philadelphia, PA: 746,197
Harris, TX: 685,264
Orange, CA: 657,433
Allegheny, PA: 647,857
Middlesex, MA: 643,382
Nassau, NY: 635,756
San Diego, CA: 633,795
Queens, NY: 627,503
Cuyahoga, OH: 623,222
Brooklyn, NY: 613,643
King, WA: 550,119
Dade, FL: 521,942
Hennepin, MN: 483,378
Dallas, TX: 464,385
Manhattan, NY: 460,838
Suffolk, NY: 460,048
Milwaukee, WI: 456,160
Erie, NY: 452,843
St Louis County, MO: 452,626
Santa Clara, CA: 443,138
Bergen, NJ: 424,853
Maricopa, AZ: 418,841
Oakland, MI: 416,205
Alameda, CA: 407,681
Westchester, NY: 384,296
Hartford, CT: 368,494
Fairfield, CT: 360,224
Hamilton, OH: 353,079
Broward, FL: 342,343
Franklin, OH: 340,712
The Bronx, NY: 337,391
New Haven, CT: 334,189
Marion, IN: 325,576
Essex, NJ: 315,812
Monroe, NY: 303,434
Norfolk, MA: 302,616
Essex, MA: 301,444
Pinellas, FL: 295,569
Worcester, MA: 285,245
Shelby, TN: 279,601
Sacramento, CA: 275,876
Montgomery, PA: 273,169

(45 counties; Ford carried 21)

1972 (Threshold: 259,146.77)
Los Angeles, CA: 2,830,370
Cook, IL: 2,311,037
Wayne, MI: 966,877
Philadelphia, PA: 783,970
Brooklyn, NY: 763,620
Queens, NY: 756,087
Nassau, NY: 693,027
Allegheny, PA: 668,535
Cuyahoga, OH: 659,751
Orange, CA: 656,653
Middlesex, MA: 617,651
San Diego, CA: 601,137
Harris, TX: 584,531
Manhattan, NY: 534,863
King, WA: 529,694
Erie, NY: 476,023
Alameda, CA: 471,195
Santa Clara, CA: 457,293
Suffolk, NY: 449,898
Hennepin, MN: 443,358
The Bronx, NY: 441,174
Dallas, TX: 438,795
Bergen, NJ: 436,894
Dade, FL: 435,763
St Louis County, MO: 424,948
Westchester, NY: 418,435
Milwaukee, WI: 416,677
Oakland, MI: 378,851
Hartford, CT: 372,586
Hamilton, OH: 364,385
Fairfield, CT: 364,366
Maricopa, AZ: 353,000
Franklin, OH: 344,808
New Haven, CT: 340,323
Essex, NJ: 338,888
Monroe, NY: 317,305
Marion, IN: 309,766
San Francisco, CA: 304,770
Essex, MA: 297,084
Sacramento, CA: 288,221
Norfolk, MA: 286,749
Delaware, PA: 274,451
Worcester, MA: 273,127
Broward, FL: 271,409
Montgomery, PA: 270,018
Baltimore City, MD: 264,652
Providence, RI: 259,156

(47 counties; McGovern carried 13)

1968 (Threshold: 243,999.993)
Los Angeles, CA: 2,812,982
Cook, IL: 2,336,538
Wayne, MI: 1,034,260
Philadelphia, PA: 850,117
Brooklyn, NY: 774,969
Queens, NY: 765,912
Allegheny, PA: 713,817
Cuyahoga, OH: 673,839
Nassau, NY: 643,195
Middlesex, MA: 577,596
Manhattan, NY: 529,392
Orange, CA: 498,707
King, WA: 474,935
Harris, TX: 471,037
San Diego, CA: 464,863
Erie, NY: 453,165
The Bronx, NY: 444,157
Bergen, NJ: 413,437
Alameda, CA: 407,349
Hennepin, MN: 407,024
Milwaukee, WI: 401,936
Westchester, NY: 400,807
St Louis County, MO: 385,375
Suffolk, NY: 374,767
Hamilton, OH: 365,483
Dade, FL: 365,302
Dallas, TX: 363,554
Santa Clara, CA: 358,367
Essex, NJ: 357,059
Oakland, MI: 345,458
Hartford, CT: 339,701
Fairfield, CT: 334,292
New Haven, CT: 314,432
Marion, IN: 310,922
San Francisco, CA: 299,947
Monroe, NY: 296,755
Baltimore City, MD: 289,884
Franklin, OH: 287,624
Essex, MA: 281,685
Maricopa, AZ: 274,651
Suffolk, MA: 268,977
Delaware, PA: 266,436
Norfolk, MA: 266,206
Worcester, MA: 265,179
Montgomery, PA: 260,732
Providence, RI: 249,940
Hudson, NJ: 244,560

(47 counties; Nixon carried 19)

1964 (Threshold: 235,464.3)
Los Angeles, CA: 2,730,918
Cook, IL: 2,432,899
Wayne, MI: 1,094,724
Brooklyn, NY: 915,503
Philadelphia, PA: 913,472
Queens, NY: 816,828
Allegheny, PA: 719,725
Cuyahoga, OH: 689,347
Nassau, NY: 632,115
Manhattan, NY: 625,719
Middlesex, MA: 576,810
The Bronx, NY: 539,594
Erie, NY: 471,576
King, WA: 450,640
Milwaukee, WI: 439,459
Alameda, CA: 427,340
San Diego, CA: 426,286
Orange, CA: 401,165
Hennepin, MN: 396,727
Essex, NJ: 396,477
Bergen, NJ: 393,465
Westchester, NY: 393,235
Harris, TX: 382,985
Hamilton, OH: 360,306
St Louis County, MO: 348,620
Hartford, CT: 329,504
Dade, FL: 326,421
Suffolk, NY: 325,333
San Francisco, CA: 323,908
Fairfield, CT: 320,619
Santa Clara, CA: 320,527
Baltimore City, MD: 316,805
New Haven, CT: 316,570
Dallas, TX: 304,158
Suffolk, MA: 298,254
Oakland, MI: 297,508
Marion, IN: 296,381
Franklin, OH: 285,872
Monroe, NY: 285,582
Essex, MA: 282,945
Hudson, NJ: 272,009
Worcester, MA: 271,631
St Louis City, MO: 267,562
Maricopa, AZ: 265,326
Providence, RI: 262,897
Delaware, PA: 259,095
Norfolk, MA: 256,012
Union, NJ: 249,347
Multnomah, OR: 243,739
Jackson, MO: 240,056
Montgomery, PA: 239,075
...
Jefferson, AL: 138,838

(51 counties; Goldwater carried three)

1960 (Threshold: 229,441.6)
Los Angeles, CA: 2,634,499
Cook, IL: 2,445,269
Wayne, MI: 1,171,909
Brooklyn, NY: 977,306
Philadelphia, PA: 915,277
Queens, NY: 815,899
Allegheny, PA: 750,718
Cuyahoga, OH: 717,086
Manhattan, NY: 635,567
Middlesex, MA: 603,516
Nassau, NY: 588,319
The Bronx, NY: 574,282
Erie, NY: 489,564
Milwaukee, WI: 445,807
King, WA: 440,810
Alameda, CA: 402,000
Westchester, NY: 396,663
San Diego, CA: 395,421
Essex, NJ: 393,623
Hennepin, MN: 388,181
Hamilton, OH: 387,283
Bergen, NJ: 381,808
San Francisco, CA: 342,219
Suffolk, MA: 339,617
Hartford, CT: 331,864
New Haven, CT: 325,539
Harris, TX: 325,399
St Louis County, MO: 324,500
Dade, FL: 317,620
Baltimore City, MD: 317,457
Fairfield, CT: 314,226
St Louis City, MO: 303,650
Oakland, MI: 298,562
Essex, MA: 295,081
Hudson, NJ: 291,292
Monroe, NY: 289,948
Marion, IN: 288,206
Orange, CA: 287,599
Worcester, MA: 286,333
Suffolk, NY: 280,945
Providence, RI: 280,042
Franklin, OH: 271,461
Jackson, MO: 266,458
Delaware, PA: 260,783
Norfolk, MA: 257,721
Multnomah, OR: 251,882
Santa Clara, CA: 250,092
Union, NJ: 245,008
Dallas, TX: 240,299
Jefferson, KY: 235,755
Montgomery, PA: 235,326

(51 counties; Nixon carried 22)

1956 (Threshold: 206,737.8)
Cook, IL: 2,276,844
Los Angeles, CA: 2,275,424
Wayne, MI: 1,148,245
Brooklyn, NY: 1,018,479
Philadelphia, PA: 892,321
Queens, NY: 787,265
Allegheny, PA: 702,030
Manhattan, NY: 678,317
Cuyahoga, OH: 658,032
The Bronx, NY: 601,588
Middlesex, MA: 561,373
Nassau, NY: 539,463
Erie, NY: 459,649
Milwaukee, WI: 407,318
Essex, NJ: 388,253
King, WA: 386,223
Westchester, NY: 377,078
Alameda, CA: 368,131
Suffolk, MA: 355,686
Bergen, NJ: 338,113
San Francisco, CA: 336,967
Hamilton, OH: 335,806
Hennepin, MN: 333,112
St Louis City, MO: 332,255
Baltimore City, MD: 318,847
San Diego, CA: 303,605
New Haven, CT: 303,423
Hartford, CT: 302,817
Hudson, NJ: 297,585
Fairfield, CT: 284,731
Essex, MA: 276,453
Providence, RI: 275,721
Monroe, NY: 274,931
Worcester, MA: 271,870
Marion, IN: 262,347
St Louis County, MO: 259,992
Jackson, MO: 255,704
Harris, TX: 254,549
Oakland, MI: 253,418
Multnomah, OR: 245,769
Dade, FL: 236,522
Franklin, OH: 230,396
Norfolk, MA: 229,996
Delaware, PA: 226,210
Denver, CO: 217,121
Union, NJ: 216,414
Suffolk, NY: 216,232

(47 counties; Stevenson carried eight)

1952 (Threshold: 205,839.81)
Cook, IL: 2,367,939
Los Angeles, CA: 2,274,540
Brooklyn, NY: 1,123,249
Wayne, MI: 1,083,381
Philadelphia, PA: 958,547
Queens, NY: 789,642
Manhattan, NY: 765,155
Allegheny, PA: 733,072
Cuyahoga, OH: 654,427
The Bronx, NY: 648,753
Middlesex, MA: 554,605
Erie, NY: 451,249
Nassau, NY: 438,090
Milwaukee, WI: 426,006
Essex, NJ: 407,635
Suffolk, MA: 404,879
Alameda, CA: 383,294
St Louis City, MO: 381,148
San Francisco, CA: 374,700
King, WA: 371,771
Westchester, NY: 352,170
Baltimore City, MD: 349,858
Hamilton, OH: 348,475
Hennepin, MN: 336,841
Hudson, NJ: 324,280
Bergen, NJ: 307,502
Providence, RI: 304,008
New Haven, CT: 303,541
Hartford, CT: 297,714
San Diego, CA: 293,034
Essex, MA: 280,409
Worcester, MA: 275,637
Fairfield, CT: 275,493
Jackson, MO: 272,297
Marion, IN: 271,939
Monroe, NY: 270,400
Harris, TX: 254,497
Multnomah, OR: 241,059
Franklin, OH: 230,514
Norfolk, MA: 215,361
Dade, FL: 215,196
Denver, CO: 213,563
St Louis County, MO: 212,480
Delaware, PA: 210,748

(44 counties; Stevenson carried 12)

1948 (Threshold: 162,645.12)
Cook, IL: 2,245,899
Los Angeles, CA: 1,729,082
Brooklyn, NY: 1,083,801
Philadelphia, PA: 885,297
Wayne, MI: 846,106
Manhattan, NY: 738,237
Queens, NY: 639,543
The Bronx, NY: 622,355
Allegheny, PA: 594,506
Cuyahoga, OH: 490,628
Middlesex, MA: 485,908
Suffolk, MA: 385,067
Erie, NY: 383,372
San Francisco, CA: 350,709
St Louis City, MO: 343,770
Essex, NJ: 343,567
Milwaukee, WI: 342,910
Alameda, CA: 323,331
Hudson, NJ: 304,653
King, WA: 291,635
Westchester, NY: 289,765
Hamilton, OH: 288,413
Hennepin, MN: 282,234
Nassau, NY: 265,238
Baltimore City, MD: 255,363
New Haven, CT: 248,993
Essex, MA: 246,371
Providence, RI: 245,748
Worcester, MA: 244,757
Hartford, CT: 235,293
Monroe, NY: 227,790
Jackson, MO: 226,527
Bergen, NJ: 217,131
Fairfield, CT: 217,072
San Diego, CA: 205,459
Marion, IN: 204,013
Multnomah, OR: 189,028
Franklin, OH: 184,999
Norfolk, MA: 176,737
Bristol, MA: 172,551
Denver, CO: 169,067
Hampden, MA: 167,720

(42 counties; Dewey carried 11)

1944 (Threshold: 159,923.54)
Cook, IL: 2,206,191
Los Angeles, CA: 1,561,564
Brooklyn, NY: 1,158,364
Wayne, MI: 875,093
Philadelphia, PA: 845,630
Manhattan, NY: 772,777
The Bronx, NY: 665,035
Queens, NY: 660,376
Allegheny, PA: 614,301
Cuyahoga, OH: 548,483
Middlesex, MA: 447,080
Erie, NY: 383,235
Suffolk, MA: 374,487
Essex, NJ: 360,742
Milwaukee, WI: 354,830
San Francisco, CA: 344,731
St Louis City, MO: 339,919
Hudson, NJ: 309,135
Hamilton, OH: 299,430
Alameda, CA: 293,987
King, WA: 286,604
Westchester, NY: 282,982
Baltimore City, MD: 276,310
Hennepin, MN: 267,320
Nassau, NY: 238,801
New Haven, CT: 234,144
Monroe, NY: 232,273
Essex, MA: 230,756
Providence, RI: 224,727
Hartford, CT: 224,218
Marion, IN: 223,837
Worcester, MA: 222,258
Bergen, NJ: 219,752
Jackson, MO: 209,632
Fairfield, CT: 205,297
Franklin, OH: 188,686
Multnomah, OR: 186,218
Denver, CO: 177,091
Norfolk, MA: 167,479
San Diego, CA: 166,764
Union, NJ: 164,625

(41 counties; Dewey carried 12)

1940 (Threshold: 166,340.4)
Cook, IL: 2,114,807
Los Angeles, CA: 1,415,269
Brooklyn, NY: 1,145,567
Philadelphia, PA: 891,486
Manhattan, NY: 778,099
Wayne, MI: 731,987
Allegheny, PA: 634,060
The Bronx, NY: 624,204
Queens, NY: 613,954
Cuyahoga, OH: 556,188
Middlesex, MA: 463,436
St Louis City, MO: 402,451
Suffolk, MA: 384,145
Erie, NY: 374,435
Milwaukee, WI: 351,197
Essex, NJ: 344,034
Hudson, NJ: 316,508
Baltimore City, MD: 315,996
San Francisco, CA: 311,878
Hamilton, OH: 303,640
Westchester, NY: 293,691
Hennepin, MN: 270,358
Alameda, CA: 268,496
Marion, IN: 247,539
Providence, RI: 244,921
Essex, MA: 243,735
King, WA: 241,803
Jackson, MO: 239,219
Monroe, NY: 236,095
Worcester, MA: 234,108
New Haven, CT: 229,689
Nassau, NY: 217,293
Bergen, NJ: 208,823
Hartford, CT: 202,953
Franklin, OH: 189,134
Fairfield, CT: 185,707
Luzerne, PA: 181,884
Denver, CO: 173,371
Multnomah, OR: 172,313

(39 counties; Willkie carried eight)

1936 (Threshold: 152,158.997)
Cook, IL: 2,009,457
Los Angeles, CA: 1,130,415
Brooklyn, NY: 974,301
Philadelphia, PA: 892,750
Manhattan, NY: 711,253
Wayne, MI: 626,120
Allegheny, PA: 562,176
The Bronx, NY: 528,818
Queens, NY: 493,009
Cuyahoga, OH: 475,418
Middlesex, MA: 419,520
St Louis City, MO: 396,830
Suffolk, MA: 350,010
Erie, NY: 342,208
Essex, NJ: 319,441
Baltimore City, MD: 310,294
Hudson, NJ: 300,559
Milwaukee, WI: 296,958
Jackson, MO: 295,319
Hamilton, OH: 280,436
San Francisco, CA: 265,001
Westchester, NY: 261,569
Hennepin, MN: 245,480
Providence, RI: 238,080
Alameda, CA: 234,686
Essex, MA: 222,999
Marion, IN: 216,550
Worcester, MA: 210,764
Monroe, NY: 210,523
King, WA: 210,045
New Haven, CT: 204,611
Luzerne, PA: 188,479
Bergen, NJ: 181,878
Hartford, CT: 176,318
Nassau, NY: 172,779
Fairfield, CT: 163,263
Franklin, OH: 158,047
Denver, CO: 152,492
Multnomah, OR: 152,319
...
Norfolk, MA: 148,890

(39 counties; Landon carried three)

1932 (Threshold: 132,506.3)
Cook, IL: 1,664,232
Los Angeles, CA: 969,594
Brooklyn, NY: 769,008
Philadelphia, PA: 607,014
Manhattan, NY: 565,205
Wayne, MI: 543,601
The Bronx, NY: 399,919
Queens, NY: 398,141
Cuyahoga, OH: 370,578
Middlesex, MA: 365,700
Allegheny, PA: 359,003
St Louis City, MO: 357,105
Suffolk, MA: 296,061
Essex, NJ: 290,772
Erie, NY: 282,930
Milwaukee, WI: 259,388
Hudson, NJ: 257,019
Jackson, MO: 256,885
Hamilton, OH: 249,076
Baltimore City, MD: 247,232
San Francisco, CA: 223,197
Westchester, NY: 220,788
Hennepin, MN: 217,566
Marion, IN: 212,664
Providence, RI: 206,544
Alameda, CA: 204,452
Essex, MA: 193,018
Monroe, NY: 185,960
King, WA: 184,031
Worcester, MA: 180,400
New Haven, CT: 174,141
Bergen, NJ: 165,743
Hartford, CT: 150,153
Fairfield, CT: 144,697
Nassau, NY: 144,100
Jefferson, KY: 141,096
Denver, CO: 136,558
Onondaga, NY: 133,219
Multnomah, OR: 132,743

(39 counties; Hoover carried 13)

1928 (Threshold: 122,690.04)
Cook, IL: 1,540,171
Los Angeles, CA: 731,301
Philadelphia, PA: 700,596
Brooklyn, NY: 679,837
Manhattan, NY: 521,558
Wayne, MI: 426,718
Allegheny, PA: 379,209
Cuyahoga, OH: 364,108
Middlesex, MA: 363,841
Queens, NY: 345,556
The Bronx, NY: 343,947
St Louis City, MO: 339,194
Suffolk, MA: 306,130
Essex, NJ: 288,514
Erie, NY: 281,789
Baltimore City, MD: 263,058
Hamilton, OH: 258,692
Hudson, NJ: 254,071
Jackson, MO: 223,677
Hennepin, MN: 208,447
Milwaukee, WI: 206,237
Westchester, NY: 195,544
San Francisco, CA: 195,468
Essex, MA: 192,810
Marion, IN: 184,100
Providence, RI: 183,637
Alameda, CA: 181,194
Worcester, MA: 181,010
Monroe, NY: 179,078
New Haven, CT: 165,048
Jefferson, KY: 162,613
King, WA: 146,678
Hartford, CT: 142,995
Luzerne, PA: 141,411
Bergen, NJ: 140,067
Franklin, OH: 139,712
Onondaga, NY: 133,716
Fairfield, CT: 127,948
Lucas, OH: 124,081
Multnomah, OR: 122,859

(40 counties; Smith carried 12)

1924 (Threshold: 96,990.4)
Cook, IL: 1,113,652
Brooklyn, NY: 498,687
Manhattan, NY: 463,326
Los Angeles, CA: 457,457
Philadelphia, PA: 447,022
Wayne, MI: 335,336
St Louis City, MO: 264,597
Cuyahoga, OH: 264,066
Middlesex, MA: 255,235
Allegheny, PA: 253,013
Suffolk, MA: 221,993
The Bronx, NY: 216,657
Hudson, NJ: 193,952
Erie, NY: 191,480
Hamilton, OH: 191,029
Queens, NY: 188,169
Essex, NJ: 186,673
Jackson, MO: 175,982
Hennepin, MN: 171,327
Baltimore City, MD: 163,252
Providence, RI: 161,550
Marion, IN: 160,880
San Francisco, CA: 153,920
Milwaukee, WI: 148,029
Monroe, NY: 141,128
Essex, MA: 139,550
Worcester, MA: 133,576
Westchester, NY: 133,035
Alameda, CA: 132,490
New Haven, CT: 120,496
Jefferson, KY: 117,586
King, WA: 112,940
Franklin, OH: 107,295
Onondaga, NY: 100,769
Hartford, CT: 99,111
Multnomah, OR: 97,764
...
Orleans, LA: 47,791

(36 counties; Davis carried one; La Follette carried one)  

1920 (Threshold: 89,217.3)
Cook, IL: 893,137
Manhattan, NY: 464,420
Brooklyn, NY: 462,248
Philadelphia, PA: 419,212
Wayne, MI: 294,943
St Louis City, MO: 282,652
Los Angeles, CA: 257,770
Cuyahoga, OH: 231,279
Middlesex, MA: 224,078
Baltimore City, MD: 220,146
Allegheny, PA: 200,716
Hamilton, OH: 196,966
The Bronx, NY: 187,329
Suffolk, MA: 186,098
Hudson, NJ: 170,793
Essex, NJ: 163,848
Jackson, MO: 158,214
Erie, NY: 157,796
San Francisco, CA: 147,421
Marion, IN: 145,571
Milwaukee, WI: 142,311
Hennepin, MN: 140,169
Queens, NY: 137,324
Essex, MA: 132,264
Providence, RI: 129,791
Jefferson, KY: 125,549
Worcester, MA: 118,372
Monroe, NY: 115,721
Westchester, NY: 111,335
Franklin, OH: 110,064
New Haven, CT: 109,474
King, WA: 107,124
Alameda, CA: 105,889
Montgomery, OH: 89,975
...
Orleans, LA (50,543) (largest Cox county)
...
Jefferson, AL: 32,939

(34 counties; Cox carried none)

1916 (Threshold: 46,341.5 [1/4 of 1% of nat'l popular vote])
Cook, IL: 849,913
Philadelphia, PA: 290,601
Los Angeles, CA: 267,921
Manhattan, NY: 265,560
Brooklyn, NY: 257,457
St Louis City, MO: 162,032
San Francisco, CA: 149,152
Allegheny, PA: 140,264
Wayne, MI: 135,184
Cuyahoga, OH: 128,900
Hamilton, OH: 120,069
Middlesex, MA: 113,072
Baltimore City, MD: 112,413
Suffolk, MA: 106,148
Erie, NY: 102,460
Alameda, CA: 102,131
The Bronx, NY: 96,204
King, WA: 95,708
Essex, NJ: 91,439
Hudson, NJ: 89,205
Multnomah, OR: 80,235
Milwaukee, WI: 80,011
Marion, IN: 79,030
Jackson, MO: 79,029
Essex, MA: 71,095
Queens, NY: 68,595
Hennepin, MN: 68,556
Denver, CO: 68,512
Providence, RI: 65,892
Monroe, NY: 63,863
New Haven, CT: 63,286
Worcester, MA: 61,680
Franklin, OH: 59,727
Westchester, NY: 58,380
Jefferson, KY: 58,314
Lucas, OH: 50,626
Onondaga, NY: 50,253
Salt Lake, UT: 50,189
Hartford, CT: 49,765
Fairfield, CT: 48,277
Luzerne, PA: 47,179
Montgomery, OH: 46,875
...
Orleans, LA: 33,983

(1/3 of 1% in this election was 61,788.6 votes; the 31 counties above the line cast above 1/3 of 1%) 

(42 counties; Hughes carried 22)

(Only election in the 20th century in which a winning nominee's best raw vote margin county did not cast at least 1/3 of 1% of the national vote; this wouldn't happen again until 2016 [and 1916 and 2016 are the only instances of this I am aware of at all; Grover Cleveland's was Manhattan]) 

1912 (Threshold: 50,162.8)
Cook, IL: 429,312
Manhattan, NY: 346,373
Philadelphia, PA: 251,690
Brooklyn, NY: 243,619
Los Angeles, CA: 165,296
St Louis City, MO: 140,327
Allegheny, PA: 126,386
Hamilton, OH: 109,949
Middlesex, MA: 102,867
Cuyahoga, OH: 102,624
San Francisco, CA: 101,148
Baltimore City, MD: 99,322
Suffolk, MA: 97,851
Wayne, MI: 88,421
Erie, NY: 83,835
Essex, NJ: 80,601
Hudson, NJ: 77,104
King, WA: 71,309
Milwaukee, WI: 71,302
Marion, IN: 67,408
Essex, MA: 66,639
Alameda, CA: 66,452
Jackson, MO: 63,194
Denver, CO: 60,016
Worcester, MA: 58,776
Providence, RI: 58,409
New Haven, CT: 56,186
Queens, NY: 55,573
Westchester, NY: 53,399
Monroe, NY: 52,605
Jefferson, KY: 52,305
Franklin, OH: 50,715

(32 counties; Taft carried three)

1908 (Threshold: 49,630.8)
Cook, IL: 415,091
Manhattan, NY: 346,612
Philadelphia, PA: 268,141
Brooklyn, NY: 236,570
St Louis City, MO: 140,550
Allegheny, PA: 121,905
Hamilton, OH: 112,946
Baltimore City, MD: 103,423
Cuyahoga, OH: 101,729
Erie, NY: 99,660
Middlesex, MA: 95,887
Suffolk, MA: 95,539
Essex, NJ: 87,004
Hudson, NJ: 85,796
Wayne, MI: 77,840
Milwaukee, WI: 73,456
Los Angeles, CA: 73,077
Marion, IN: 70,580
Denver, CO: 65,707
Essex, MA: 61,373
San Francisco, CA: 60,124
Jackson, MO: 59,760
Monroe, NY: 58,649
New Haven, CT: 57,424
Worcester, MA: 55,425
Jefferson, KY: 54,700
Franklin, OH: 54,097
Providence, RI: 53,771
Westchester, NY: 50,422
...
Jefferson, AL: 10,707

(29 counties; Bryan carried three)

1904 (Threshold: 33,812.5 [1/4 of 1% of nat'l popular vote])
Cook, IL: 392,945
Manhattan, NY: 368,072
Philadelphia, PA: 281,654
Brooklyn, NY: 235,317
Allegheny, PA: 118,405
St Louis City, MO: 115,792
Suffolk, MA: 98,964
Hamilton, OH: 98,038
Baltimore City, MD: 97,537
Middlesex, MA: 91,868
Cuyahoga, OH: 91,256
Erie, NY: 89,132
Essex, NJ: 79,863
Hudson, NJ: 78,613
Milwaukee, WI: 70,512
Wayne, MI: 69,750
San Francisco, CA: 65,427
Denver, CO: 63,153
Marion, IN: 59,963
Essex, MA: 59,392
New Haven, CT: 56,570
Worcester, MA: 53,461
Monroe, NY: 51,053
Providence, RI: 50,698
Los Angeles, CA: 48,883
Jackson, MO: 48,521
Jefferson, KY: 45,959
Westchester, NY: 44,879
Franklin, OH: 44,622
Albany, NY: 44,442
Onondaga, NY: 43,317
Luzerne, PA: 42,895
Hennepin, MN: 42,648
Hartford, CT: 41,382
Fairfield, CT: 40,349
Montgomery, OH: 37,725
Oneida, NY: 34,571
Lancaster, PA: 34,077
Lucas, OH: 34,045
Queens, NY: 34,017

(1/3 of 1% in this election was 45,083.34 votes; the 27 counties above the line cast above 1/3 of 1%)

(40 counties; Parker carried six)

1900 (Threshold: 34,993.6 [1/4 of 1% of nat'l popular vote])
Cook, IL: 401,134
Manhattan, NY: 346,487
Philadelphia, PA: 234,889
Brooklyn, NY: 219,848
St Louis City, MO: 124,574
Baltimore City, MD: 113,008
Allegheny, PA: 102,624
Hamilton, OH: 97,515
Suffolk, MA: 91,365
Cuyahoga, OH: 90,288
Erie, NY: 86,657
Middlesex, MA: 81,955
Essex, NJ: 73,288
Hudson, NJ: 72,627
Wayne, MI: 66,356
Milwaukee, WI: 66,243
San Francisco, CA: 63,202
Arapahoe, CO: 60,483
Essex, MA: 56,947
New Haven, CT: 54,245
Marion, IN: 53,966
Worcester, MA: 51,582
Monroe, NY: 48,870
Jefferson, KY: 46,536
Jackson, MO: 45,206
Hennepin, MN: 43,095
Albany, NY: 42,752
Franklin, OH: 42,636
Providence, RI: 41,691
Onondaga, NY: 40,957
Luzerne, PA: 39,717
Westchester, NY: 38,777
Hartford, CT: 37,846
Fairfield, CT: 37,332
Montgomery, OH: 36,614

(1/3 of 1% in this election was 46,658.1 votes; the 23 counties above the line cast above 1/3 of 1%)

(35 counties; Bryan carried five)

1896 (Threshold: 34,842.4 [1/4 of 1% of nat'l popular vote])
Cook, IL: 379,338
Manhattan, NY: 308,232
Philadelphia, PA: 244,887
Brooklyn, NY: 193,676
St Louis City, MO: 116,996
Allegheny, PA: 108,174
Baltimore City, MD: 106,601
Hamilton, OH: 96,475
Suffolk, MA: 89,551
Cuyahoga, OH: 81,490
Middlesex, MA: 80,266
Erie, NY: 77,879
Essex, NJ: 65,525
Milwaukee, WI: 64,344
Wayne, MI: 64,158
Hudson, NJ: 64,033
San Francisco, CA: 63,086
Essex, MA: 53,964
Hartford, CT: 52,286
Arapahoe, CO: 49,134
Marion, IN: 48,860
Worcester, MA: 48,493
Hennepin, MN: 48,288
Jefferson, KY: 47,262
Monroe, NY: 44,818
Luzerne, PA: 41,248
Albany, NY: 40,834
Providence, RI: 40,320
Onondaga, NY: 40,141
Jackson, MO: 39,862
Franklin, OH: 39,053
Fairfield, CT: 36,063
unknown county, CT: 35,998*
Montgomery, OH: 34,232
Los Angeles, CA: 34,042
Lancaster, PA: 33,490
Berks, PA: 33,082
Westchester, NY: 32,434
Schuylkill, PA: 32,407
Queens, NY: 32,213
Lackawanna, PA: 31,605
Kent, MI: 31,384
Oneida, NY: 31,007
Rensselaer, NY: 30,914
Lucas, OH: 30,776
Ramsey, MN: 30,387
Bristol, MA: 28,435
Montgomery, PA: 28,294

* This is purportedly the number of votes cast by Middlesex County, CT in 1896, but I am suspicious of these figures because in 1900, the same county is said to have cast 8,223 votes. I suspect the figures for Middlesex and New Haven Counties are mixed up before 1900. Both voted for McKinley.

(1/3 of 1% in this election was 46,456.5 votes; the 24 counties above the line cast above 1/3 of 1%) 

(33 counties; Bryan carried two)

The counties below the second line cast between 1/5 (~ 27,873.9 votes) and 1/4 of 1% of the national popular vote, although in this light, it is worth noting that additional states for which there are no data in 1896 are Delaware (New Castle County cast 29,384 votes in 1912), Louisiana (Orleans Parish cast 33,029 votes in 1912), Texas (Dallas County cast 9,682 votes in 1912; Harris County cast 9,066), and West Virginia (Kanawha County cast 17,869 votes in 1912). Assuming none of those counties cast over 27,873 votes in 1896, this makes for a list of the 48 most vote-casting counties in 1896, of which Bryan carried three. (Orleans Parish, which seems the likeliest to have done so, voted for Bryan. New Castle voted for McKinley.)

1892 (Threshold: 40,226.8) (No data for New Jersey)
Manhattan, NY: 284,984
Cook, IL: 261,330
Philadelphia, PA: 203,102
Brooklyn, NY: 176,385
Baltimore City, MD: 89,457
Hamilton, OH: 82,040
Suffolk, MA: 81,392
Allegheny, PA: 78,504
Middlesex, MA: 77,090
St Louis City, MO: 71,139
Erie, NY: 68,430
San Francisco, CA: 58,435
Cuyahoga, OH: 58,414
Wayne, MI: 55,138
Essex, MA: 53,383
Milwaukee, WI: 51,008
Worcester, MA: 49,471
Hartford, CT: 46,058
Monroe, NY: 41,488
Hennepin, MN: 41,260
Marion, IN: 40,926

(At least 21 counties; Harrison carried at least nine. Cleveland carried both Essex and Hudson Counties, NJ in 1892.)

---

There are some exceptions, but in general, counties have tended to stay on the list for sustained periods once they enter it, and not to return once they leave it. Some different counties' tenures on the list of mega counties (italicised counties were mega counties in 2020):

Allegheny, PA: ...1880-2020

Baltimore City, MD: ...1892-1972 

Brooklyn, NY: ...1884-2020 

Cook, IL: ...1892-2020

Cuyahoga, OH: 1864-2020

Erie, NY: ...1884-2008

Essex, MA: ...1876-1980, 1988

Essex, NJ: ...1896-1976, 1984

Hamilton, OH: ...1856-2004 

Hartford, CT: ...1884-1896, 1924-2000 

Hennepin, MN: ...1892-1896, 1916-2020

Hudson, NJ: ...1896-1968 

Manhattan, NY: ...1884-2020

Marion, IN: 1892-1988

Middlesex, MA: ...1876-2020

Milwaukee, WI: ...1892-2012

Monroe, NY: 1888-1892, 1900-1988

Philadelphia, PA: ...1880-2020

Saint Louis City, MO: ...1888-1964

San Francisco, CA: ...1880-1972 

Suffolk, MA: ...1876-1968

Wayne, MI: ...1884-2020 

Worcester, MA: ...1876-1912, 1920-1976

Jefferson, KY: 1896, 1904-1912, 1920-1932, 1960

New Haven, CT: 1900-1996 

Denver, CO: 1904-1916, 1932-1956 

Jackson, MO: 1904-1964

Los Angeles, CA: 1904-2020

Franklin, OH: 1908-1912, 1920-1928, 1936-2020

Westchester, NY: 1908-1912, 1920-2000

Alameda, CA: 1912-2020 

King, WA: 1912-2020

Queens, NY: 1912-2020 

The Bronx, NY: 1916-1976, 1984

Multnomah, OR: 1916, 1924-1964 

Onondaga, NY: 1924-1932

Bergen, NJ: 1928-2000 

Fairfield, CT: 1928-2000

Nassau, NY: 1932-2020

Norfolk, MA: 1944-1980, 1988

San Diego, CA: 1944-2020

Union, NJ: 1944, 1956-1964

Dade, FL: 1952-2020

Delaware, PA: 1952-1972

Harris, TX: 1952-2020

Saint Louis County, MO: 1952-2020

Oakland, MI: 1956-2020

Suffolk, NY: 1956-2020 

Dallas, TX: 1960-2020

Montgomery, PA: 1960-1976 

Orange, CA: 1960-2020

Santa Clara, CA: 1960-2020

Maricopa, AZ: 1964-2020 

Broward, FL: 1972-2020

Sacramento, CA: 1972-2020

Pinellas, FL: 1976-2020

Shelby, TN: 1976-1996

Bexar, TX: 1980-2020

San Bernardino, CA: 1980-2020

Tarrant, TX: 1980-2020

Contra Costa, CA: 1984-2020

DuPage, IL: 1988-2000

Fairfax, VA: 1988-2020

Montgomery, MD: 1988-2020

Palm Beach, FL: 1988-2020

Riverside, CA: 1988-2020

Clark, NV: 2000-2020

Hillsborough, FL: 2000-2020

Orange, FL: 2008-2020

Mecklenburg, NC: 2012-2020

Wake, NC: 2012-2020

Travis, TX: 2016-2020

Salt Lake, UT: 2020

---

Salena Zito is pointing out that Trump did historically badly in the country's mega counties in 2016. This is plain to see. However, as of 2000 and 2004, George W. Bush was also doing historically badly in the country's mega counties for a winning or narrowly losing candidate. His performance was strong only relative to later Republican nominees. 

In 2000, Bush carried 13/46 mega counties, not much better than Dole in 1996 (10/46) and about the same as his father in 1992 (14/47), as both were going down to decisive defeats. Furthermore, this was the smallest proportion of the nation's mega counties that a winning nominee had carried since at least the 19th century. In 1988, Bush Sr carried a majority of the country's mega counties (29 of 50), the last time a Republican has done so. In his narrow win in 1968, Nixon carried 19/47. In their narrow defeats in 1960 and 1976, Nixon carried 22/51 and Ford, 21/45, respectively. In 1916, Wilson carried 14/31 (or 20 of the 42 counties casting at least 1/4 of 1% of the national vote). Only in 1896 and 1948 did a nominee come close to winning despite doing worse in the country's mega counties than Bush in 2000.

Of course, from 1968 through 1996, Nixon's 1968 win would have stood as the weakest performance in the mega counties for a winning nominee since at least the 19th century. However, the proportion of mega counties Nixon carried in 1968 (40.4%) was comparable to the proportion of mega counties carried by Nixon in his narrow defeat in 1960 (43.1%) and by Ford in his narrow defeat in 1976 (46.6%) (although, curiously, it is the lowest of the three). (It is also comparable to the proportion of counties casting at least 1/3 of 1% of the national vote carried by Wilson in 1916--45.2%.) The proportion of mega counties Bush carried in 2000, on the other hand, was qualitatively lower than any of these--28.3%.

In 2004, Bush once again did historically badly for a winning or narrowly losing nominee in the country's mega counties, carrying 12 of 41, or 29.3%. 

The number of mega counties did fall somewhat sharply in 2004, and went below 45 for the first time since 1952. (In 1960, by contrast, there were 51 mega counties.) If we add the counties that cast between 1/4 (~ 305,738.4) and 1/3 of 1% of the national vote in 2004, we get a list that is numerically far more disparate to the list of mega counties in 1960 in the other direction--but it nevertheless tells us something interesting. This would be the continuation of such a list:

42. DuPage, IL: 402,446
43. Macomb, MI: 402,410
44. Fairfield, CT: 400,967
45. Bergen, NJ: 400,244
46. Montgomery, PA: 399,591
47. Westchester, NY: 395,770
48. Hartford, CT: 391,808
49. Orange, FL: 388,044
50. Duval, FL: 381,061
51. Shelby, TN: 377,282
52. Pima, AZ: 366,907
53. New Haven, CT: 366,392
54. Multnomah, OR: 362,694
55. Salt Lake, UT: 362,136
56. San Francisco, CA: 357,465
57. Baltimore County, MD: 353,479
58. Travis, TX: 352,113
59. Wake, NC: 348,844
60. Monroe, NY: 343,064
61. The Bronx, NY: 342,929
62. Worcester, MA: 340,636
63. Fulton, GA: 336,407
64. Essex, MA: 333,233
65. Norfolk, MA: 331,137
66. Mecklenburg, NC: 323,102
67. Marion, IN: 320,838
68. Bucks, PA: 319,816
69. Prince George's, MD: 318,474
70. Jackson, MO: 315,993
71. Pierce, WA: 313,331
72. Ventura, CA: 313,193

Of the 72 counties that cast at least 1/4 of 1% of the national vote in 2004, Bush carried only 18--fewer than the number of the 51 most vote-casting counties Nixon carried in 1960, or the number of the 47 most vote-casting counties Nixon carried in 1968, or than the number of the 45 most vote-casting counties Ford carried in 1976. 

In fact, we can do the same thing for 2000 to similar effect. These are the counties that cast between 1/4 (~ 263,553.6 votes) and 1/3 of 1% of the national vote that year:

47. Macomb, MI: 345,559
48. New Haven, CT: 341,099
49. Shelby, TN: 336,755
50. Montgomery, PA: 332,422
51. San Francisco, CA: 319,786
52. Monroe, NY: 317,762
53. Norfolk, MA: 317,177
54. Essex, MA: 310,333
55. Worcester, MA: 310,058
56. The Bronx, NY: 308,048
57. Salt Lake, UT: 307,258
58. Baltimore County, MD: 304,084
59. Jefferson, KY: 302,361
60. Travis, TX: 301,263
61. Multnomah, OR: 296,685
62. Pima, AZ: 287,640
63. Ventura, CA: 282,692
64. Orange, FL: 280,155
65. Marion, IN: 279,903
66. Jefferson, AL: 273,763
67. Jackson, MO: 272,062
68. Prince George's, MD: 271,909
69. Pierce, WA: 268,427
70. Wake, NC: 268,211
71. Duval, FL: 265,181

Of the 71 most vote-casting counties in 2000, Bush carried 20--again, fewer than the number of the 51 largest counties Nixon carried in 1960, or than the number of the 45 largest counties Ford carried in 1976 (and only one more than the number of the 47 largest counties Nixon carried in 1968).

---

A note on 1948

It is not surprising that William Jennings Bryan should have run a close election in 1896 despite doing historically badly in the mega counties. What is more surprising is that Dewey did so in 1948. 

When looking at specific counties on the list of mega counties in 1948, however, there are few surprises about how any of the specific mega counties voted. (Middlesex, MA is perhaps an exception.) At the time, it might have been surprising that Philadelphia, Wayne, Allegheny, Erie (NY), St Louis City, Alameda, and Multnomah voted for Truman. These had all been Republican strongholds before the New Deal (or in St Louis' case, before Al Smith, who had also carried Queens). However, 1948 was merely demonstrating the permanency of the New Deal's realignment of these places towards the Democracy. Apart from Multnomah's vote for Nixon in 1960, all these jurisdictions have gone on to vote Democratic in every subsequent close election. 

Dewey appears to have done well in many suburban counties that were still too 'emergent' to show up on a list of mega counties. This was, incidentally, largely Michael Barone's argument (in 2001) about how George W. Bush had offset his own weakness in 'major metro areas':

The fastest-growing parts of the United States are formerly rural counties on the metropolitan fringe, beyond the edge-city office centers, and are now filling up with family-sized subdivisions, outlet shopping malls, and booming mega-churches. Though many of these are within the boundaries of major metro areas, these counties tend to vote strongly Republican; and, with their growth, they have produced Republican majorities almost large enough to offset the Democratic margins in heavily black or culturally liberal central cities. These are places such as Collin County, Texas, which grew by 86 percent in the 1990s, and voted 73 percent to 24 percent for Bush; Forsyth County, Georgia, which grew by 123 percent, and voted 78 percent to 19 percent for Bush; and Douglas County, Colorado, which grew by 191 percent, and voted 65 percent to 31 percent for Bush. These edge counties are usually ignored by reporters and political scientists, who can't imagine living in such places, but they are in many ways the cutting edge of America, the wave of the future.

However, we can point out that there were fully eight counties Dewey carried in 1948, that weren't mega counties in 1948 but were a scant twelve years later, in 1960: St Louis County (MO), Oakland, Orange (CA), Suffolk (NY), Delaware (PA), Santa Clara, Union (NJ), and Montgomery (PA). In 2020--twenty years after 2000--there were only four counties that voted for Bush in 2000, that weren't mega counties in 2000 but that were in 2020: Wake and Mecklenburg, NC; Travis, TX; and Salt Lake, UT. (The same goes for 2004, except that Bush didn't carry Mecklenburg or Travis that year.) None of these counties was amongst those mentioned by Barone as examples of the fast-growing 'edge counties', Republican strength in which was continuing to establish the GOP as the party of the future as of 2001. Nor was any of them amongst the counties identified by Chris Palko as the 'top 20 conservative-friendly counties' in 2010, many of which might also have been examples of what Barone had in mind (all three of the counties Barone mentioned made Palko's list).

Conversely, two of the mega counties Bush carried in 2000--DuPage, IL and Hamilton, OH--were off the list as early as 2008, whereas every mega county Dewey carried in 1948 was still a mega county in 1960.

Looking at the number of counties candidates carried by a raw vote margin of over 100,000 votes is another rough measure of candidates' strength in large counties (one that takes into account the depth of a candidate's support in counties he does carry, as well as whether he carries them or not). In 1948, Dewey carried one county by over 100,000 votes (the first Republican to do so since 1928), and held Truman to carrying just six counties by over 100,000 votes. In 2000--with the total electorate having a little more than doubled in the interim--Bush carried three counties by over 100,000 votes, whereas his Democratic opponent carried 23 counties by over 100,000 votes, an order of magnitude more than Truman had done in 1948. Even with Bush improving to six counties won by over 100,000 votes in 2004, the same held true, as Kerry approached 30. 

(Meanwhile, in 1896, as one might expect, not only did Bryan not win any counties by over 100,000 votes [which was significantly more difficult at the time], but his largest county margin was less than a third the size of McKinley's, and was also smaller than Cleveland's in any of 1884, 1888, or 1892.)

In fact, by this metric, it is not 1948 (amongst the four close elections of the Cold War period) that seems like an outlier. Dewey's ability to draw large county margins and deny them to his Democratic opponent was bested in this era only by Gerald Ford in 1976 (amongst narrow-election Republicans), and was discernibly superior to Nixon's in either 1960 or 1968.