> 2:1 states

On the morning after the 2004 election, Tom Brokaw observed that 

[Democrats] are not going to be a national party until they can get back into the Great Plains and the Rocky Mountain West to some degree and into the South and make a stand there because they're not even close in those states. I mean, George Bush is winning by two-to-one and three-to-one in some of those states.

(Bush didn't win any states by better than 3:1; the last time that has happened is 1984, when Reagan carried Utah by better than 3:1.) 

If someone is carrying a state by better than 2:1, he or she is getting over twice as many votes as his or her closest opponent. If someone is getting > 66.6% of the vote in a state, he or she is getting over twice as many votes as his or her combined opposition (and therefore is necessarily getting over twice as many votes as his or her closest opponent). If a nominee is getting less than this but is still winning by better than two-to-one, it is at least potentially because the vote against him is divided.

In formulating different nominees' 'fornias', we looked at states where the margin was at least 20% (or 1/5) but where the winner's vote share was at least 55.5%--in other words, where the winner was beating his nearest opponent by better than 1.5:1, but could be beating his combined opposition by as 'little' as 1.25:1. 

We could follow a similar approach, and count states as being won 'by better than 2:1' only if the winner is getting at least 60% of the vote (that is, is beating his combined opposition by at least 1.5:1). (Sharon Bernstein described California as having 'broke[n] nearly two-to-one in favor of...Hillary Clinton'; Hillary Clinton's vote share in the state was 61.37% that year. The CQ Almanac has also used '60%' as a threshold for distinguishing states that supported a given nominee particularly strongly, e.g., in its recap of the 1976 election ['All four states in which Ford won at least 60 per cent of the vote were in the West'] and in its recap of the 1984 election ['Reagan received at least 60 percent of the vote in nearly two-thirds of the states...'].) What are the possible consequences of not setting such a stipulation? Well, counting states such as Alaska in 1980, Washington in 1920, and Tennessee in 1912 as being won by better than 2:1--the winners' winning percentages in those states were 54.35%, 55.96%, and 52.80%, respectively. Even in the more reasonable-seeming case of, say, North Dakota in 1936 [when FDR got 59.60% in the state--nearly our threshold], there are eight states where FDR did better than in North Dakota but did not win by better than 2:1, and counting North Dakota obscures the [possible] role of Lemke in making that state a better than 2:1 win for him.

In that case, what have been each nominees' 'better-than-2:1 states' in the past six elections? (The more lightly shaded states are ones in which the nominee got less than 2/3 of the vote.)

2020 (Biden 24, Trump 18)
2016 (Trump 18, Hillary Clinton 4)
2012 (Romney 16, Obama 7)
2008 (Obama 7, McCain 0)
2004 (Bush 17, Kerry 0)
2000 (Bush 12, Gore 0)

States that were left out of these maps due to our stipulations were Alaska in 2000 (where Bush got 58.62%) and Idaho in 2016 (where Trump got 59.26%). As if to bear out the correctness of our stipulation, Bush failed to win Alaska by better than 2:1 the second time around, and Trump failed to win Idaho by better than 2:1 the second time around--despite that in both cases, the Republican improved his vote share in the state.

In 2004, Bush did indeed win four states by better than 2:1 (Wyoming, Utah, Idaho, and Nebraska). He had (again, excluding Alaska) won three in 2000. In both cases, his opponent won none.

How unusual was this, though? Well, these are the states that were won by major-party nominees by better than 2:1 (and with more than 60% of the vote) in elections from 1836 through 1996:

1996 (Clinton 12, Dole 0)
1992 (none)
1988 (HW Bush 5, Dukakis 0)
1984 (Reagan 50, Mondale 0)
1980 (Reagan 28, Carter 0)
1976 (Carter 12, Ford 0)
1972 (Nixon 141, McGovern 0)
1968 (Humphrey 4, Nixon 0)
1964 (Johnson 101, Goldwater 17)
1960 (none)
1956 (Stevenson 12, Eisenhower 8)
1952 (Eisenhower 25, Stevenson 12)
1948 (Truman 44, Dewey 0)
1944 (Roosevelt 104, Dewey 0)
1940 (Roosevelt 113, Willkie 0)
1936 (Roosevelt 185, Landon 0)
1932 (Roosevelt 157, Hoover 0)
1928 (Hoover 42, Smith 29)
1924 (Coolidge 112, Davis 84)
1920 (Harding 241, Cox 61)
1916 (Wilson 102, Hughes 0)
1912 (Wilson 93, Taft 0)
1908 (Bryan 62, Taft 4)
1904 (Roosevelt 146, Parker 67)
1900 (Bryan 58, McKinley 4)
1896 (Bryan 80, McKinley 35)
1892 (Cleveland 30, Harrison 4)
1888 (Cleveland 61, Harrison 4)
1884 (Cleveland 22, Blaine 4)
1880 (Hancock 16, Garfield 10)
1876 (Tilden 27, Hayes 10)
1872 (Grant 44, Greeley 0)
1868 (Grant 30, Seymour 25)
1864 (Lincoln 36, McClellan 11)
1860 (Lincoln 26, Breckinridge 4)
1856 (Frémont 18, Buchanan 4)
1852 (Pierce 14, Scott 0)
1848 (Cass 4, Taylor 0)
1844 (none)
1840 (none)
1836 (van Buren 7, Whigs 0)

(Interestingly, the Whig Party proper never carried a state by better than 2:1. John Quincy Adams carried four states, worth 34 electoral votes, by better than 2:1 in 1828.)

Roughly speaking, it appears there was a relatively non-polarised period from 1836 through 1852, when neither party carried many states by better than 2:1 (and in some elections, neither carried any at all). Then, from 1856 through 1872, the Republicans routinely carried at least a couple states by better than 2:1, whereas Democrats typically carried either one or none (in 1868, Seymour carried three, while Grant carried four). 

1876 inaugurated a period of about 80 years during which Democrats almost routinely carried several states by better than 2:1, regardless of how they were doing nationally, whereas Republicans seldom carried any more than two (or, after the first couple elections in this period, one), unless they were winning a national landslide or quasi-landslide. When Republicans lost badly--or, from 1916 on, at all--it was not unusual for them to carry no states by better than 2:1.

In 1896, William McKinley carried five states by better than 2:1, but Bryan carried 12 states by better than 2:1 in the same election. This was an unusually polarised election, and it was one of only three elections between 1836 and 1964 in which the Democrats carried any states outside the South by better than 2:1, together with the FDR landslides of 1932 and 1936 (and, oh, I forgot 1868, when Seymour carried Maryland by better than 2:1). 

In 1904, TR carried 16 states, worth 146 electoral votes, by better than 2:1 (as always, with the stipulation that 'by better than 2:1' means 'and with at least 60% of the vote'). This was the most to date of any nominee, and was highly atypical for Republican nominees in the previous or next few elections. Harding, likewise, set a new record in 1920, of 16 states worth 241 electoral votes being carried by better than 2:1. It would seem one could have said at this time that Republicans carrying a large number of states by better than 2:1 was indicative of a Republican landslide, as these elections were clearly demarcated from other elections in terms of the number of states and number of electoral votes carried by the Republican by better than 2:1. (This would get fuzzier in the next two elections.) However, in the close election of 1916, Wilson carried nine states worth 102 electoral votes by better than 2:1. TR's and Harding's own opponents, Parker and Cox, carried several states worth 60-70 electoral votes by better than 2:1. 

Democrats had not won a landslide since Jackson, until FDR. One might have thought that, with the head start afforded by the Solid South, a Democratic landslide winner would exceed Harding in terms of number of states/electoral votes carried by better than 2:1, but FDR never did (although he exceeded TR in both 1932 and 1936). (FDR did exceed Harding in terms of number of states carried by better than 2:1 in 1936, carrying twenty states by better than 2:1 in that election.)

In 1952 and 1956, the Solid South was much weaker for Stevenson than for previous Democratic nominees (even those losing in landslides), as evidenced by the fact that Stevenson only ever won one state--Georgia--by better than 2:1 (and with over 60%). But Eisenhower himself fell well short of the number of states/electoral votes carried by better than 2:1 by previous Republican landslide winners, hence keeping the quasi-parity between the parties in Republican landslide wins that had been typical of the 20th century up to that point. (In 1956--his stronger national win--Eisenhower carried only two states by better than 2:1, and combined, they were worth fewer electoral votes than Georgia.)

1960 was something of a watershed. It was the first election since 1844 in which no state voted for either major party nominee by better than 2:1. Now, it had not been unusual for Republicans to not carry states by better than 2:1--they had not done so in 1916, 1932, 1936, 1940, 1944, or 1948 (whereof 1916 and 1948 had been near-wins). But Kennedy was the first Democrat since Polk not to carry any states by better than 2:1, and this was immediately after Stevenson had carried Georgia by better than 2:1 twice, despite twice losing in a landslide nationally. (Kennedy, incidentally, carried no states by better than 2:1 even if we remove the stipulation that we also mean that the nominee in question got at least 60% of the vote.) 

1960 largely began a relatively de-polarised era, like that from 1836 through 1852. There were two exceptions: 1964 and 1972. In 1964, Johnson carried seven states worth over 100 electoral votes by better than 2:1, and in 1972, Nixon carried 17 states worth well over 100 electoral votes by better than 2:1. This was not unheard of for previous landslide winners, but it was also not a given, as demonstrated by Eisenhower just a decade or two prior (as well as Hoover). More shockingly, Goldwater carried two states by better than 2:1 in his 1964 landslide defeat. 

Aside from that, however, from 1960 through 1996, in close elections, typically only one state (at most) voted for anyone by better than 2:1, and in the two decisive elections of 1988 and 1996, only one state did so (both times for the winner--and both times without quite giving the state's carrier 2/3 of its vote). In his 1984 landslide, Reagan carried 'only' 10 states worth 50 electoral votes by better than 2:1--while this may seem like a lot, and while it was more than Eisenhower managed either time, it was well short of TR in 1904, Harding in 1920, FDR in 1932 or 1936, Johnson in 1964, or Nixon in 1972. 

It would be hard to say that the Republican Party became the more 'locally intense' party during this time, especially given that in the close elections of 1968 and 1976, the only state to vote for anyone by better than 2:1, were Democratic states. But, after 1960 had become the first election in over a century in which the Democrat had failed to carry any state by better than 2:1, it was followed by 1972, 1980, 1984, 1988, and 1992. Of course, there were also a number of elections in which the Republicans failed to do so, but this would not have represented any kind of dramatic historic reversal. 

What Brokaw seemed to be noticing was that in the 2000 and 2004 elections, it was becoming clear that the Republican Party was becoming the party of greater local intensity. In 2000, George W. Bush carried three states by better than 2:1 (and furthermore, he got over 2/3 of the vote in all three, which George H. W. Bush had fallen short of in Utah in 1988, meaning 2000 was the first election in which anyone had gotten over 2/3 of the vote in a state since 1984). In 2004, he carried the same three states by better than 2:1 again, and added Nebraska (albeit without getting over 2/3 of the vote in Nebraska). All the states Bush carried by better than 2:1 were states it had been typical for Republicans to carry by better than 2:1--but only in decisive or landslide national wins, not in close elections. The last time any major party nominee had carried multiple states by better than 2:1 in a nationally close election was 1948, and it was the Democrat doing so in that case. (And even Truman fell short of getting 2/3 of any state's vote; the last time any nominee got over 2/3 of multiple states' votes in a nationally close election was, again, 1916, and, again, it was the Democrat doing so.) 

However, in 2008, Obama carried two states by better than 2:1, and McCain carried none. On the surface, this is not surprising; however, when the Democrats were the party of greater local intensity, they routinely carried states by better than 2:1 even when losing under far worse conditions nationally than those amid which McCain was losing in 2008. In the closer election of 2012, Romney carried three states by better than 2:1, and Obama carried two. Romney thereby became the first losing Republican (apart from Goldwater) to carry any state by better than 2:1 since 1892. At the same time, Obama was carrying two states by better than 2:1--Republicans had done no better than one state in 1884, 1888, 1892, 1900, or 1908, all of which were at least close and some of which they won, in some cases decisively. 

Still, it might have seemed that the GOP was remaining the party of greater local intensity, as Romney was carrying three states worth 16 electoral votes by better than 2:1, and Obama was carrying only two states, worth only seven electoral votes, by better than 2:1 (and Romney was, after all, losing). This might have continued to seem the case in 2016, as Trump carried four states by better than 2:1 (some might say five, as he did carry Idaho by better than 2:1, but with 'only' 59.26% of the vote), whilst Hillary Clinton carried only one, worth four electoral votes (and that is regardless of whether one stipulates that she had to get over 60% of the vote in a given state for it to 'count').

In 2020, Joe Biden carried three states worth 24 electoral votes by better than 2:1, and Trump carried four states worth 18 electoral votes by better than 2:1 (the same ones as he did in 2016). No Democrat had carried as many states, or as many electoral votes' worth of states, by better than 2:1 since 1964. It seems to be becoming clear that there are certain areas of the country now that are as forbiddingly Democratic as struck Brokaw as being forbiddingly Republican in 2004.

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The specific states that have voted for the parties by better than 2:1 can show interesting developments in the parties' bases over time.

On the Republican side, the biggest constant was Vermont. Vermont voted Republican by better than 2:1 in every election from 1856 through 1908. 1916 was the first two-party contest in which it did not. However, it did so again in 1920, 1924, 1928, 1952, and 1956. In 1952, it was something of a regional outlier, as Eisenhower's other > 2:1 states were all in the Plains West. 

In five elections (1884, 1888, 1892, 1900, and 1908), Vermont was the only state to vote Republican by better than 2:1. Until 2012--for the first century and a half of the party's existence (and leaving aside Goldwater)--Vermont and Massachusetts were the only states to have voted for a losing Republican by better than 2:1 (and Vermont was the only state to have voted over 66.6% for a losing Republican).

The next-biggest constants are Maine, Kansas, and Nebraska. Maine voted for Lincoln by better than 2:1 in 1860, and although it would be less consistent than Vermont in its Republicanism, it would go on to do so again in 1872, 1896, 1904, 1920, 1924, 1928, and 1956. In 1904, 1928, and 1956, it was the only New England state other than Vermont to vote Republican by better than 2:1. (In 1956, it was the only other state in the country to do so.) Massachusetts had voted Republican by better than 2:1 frequently in the party's early elections, but its last time doing so was 1924 (which was also the last time any New England state other than New Hampshire, Vermont, or Maine did so). 

New Hampshire had been--relatively speaking--frosty to the GOP within New England, which is interesting given that we will be seeing it again. As of 1956, the only time New Hampshire had ever voted Republican by better than 2:1 was in 1896. 

Kansas voted Republican by better than 2:1 in its first participating election, in 1864, and did so for the next four straight elections. In 1876 and 1880, it was the only state in the country other than Vermont to vote Republican by better than 2:1. Nebraska voted Republican by better than 2:1 in 1872. It was the only state outside New England to do so in 1872, other than Kansas and South Carolina.

Technically, Kansas and Nebraska are not the oldest > 2:1 Republican states to still be red today, since amongst the other > 2:1 Republican states in 1864, 1868, and/or 1872 were West Virginia, Missouri, Tennessee, and South Carolina. However, they are the oldest > 2:1 Republican states that went on to compile substantial records of voting Republican by better than 2:1 that are still red today. Kansas--the older and, initially, more Republican of the two--went on to vote Republican by better than 2:1 in 1904, 1924, 1928, 1952, 1972, and 1984. Nebraska went on to do so in 1904, 1920, 1952, 1972, 1980, 1984, and 2004. In 1972, they both voted for Nixon by better than 2:1 even as neither of the Dakotas did so. 

Since the Dakotas became states, they voted Republican by better than 2:1 in 1904, 1920, and 1952. As of October 1980, they had each done so thrice, whereas, during the period in which the Dakotas had been states, Kansas had done so five times, and Nebraska, four times. (The Dakotas have gone on to diverge; 1952 was the last time South Dakota has voted Republican by better than 2:1 to date, whereas North Dakota has done so in 1980 [but not 1984, oddly], 2016, and 2020.) Mark27 distinguished the Dakotas from Nebraska and Kansas by noting the Dakotas' 'prairie populism', with their greater amount of blue-leaning counties prior to 2000. And in fact, in 1988, Dukakis carried 20 counties in South Dakota and 10 in North Dakota, but only three each in Kansas and Nebraska. In 2008, Obama was able to get the Republican margin down to single digits in the Dakotas, but not in Kansas or Nebraska. In the last couple elections, the Dakotas have realigned to become the reddest of the free-soil/postbellum Plains States. 

In the elections of 1904, 1920, 1924, and 1928, the only state outside New England and the 'Haga stack' states to vote Republican by better than 2:1 in all four was Michigan. Pennsylvania did so in three of the four elections (all save 1928). In both 1904 and 1920, a broad swath of contiguous Upper Midwestern states voted Republican by better than 2:1: Minnesota, Wisconsin, Iowa, and Michigan (with the addition of Illinois in 1920). (Neither Ohio nor Indiana voted Republican by better than 2:1 in any of the four elections, or indeed has done so in any election.)

The strongest and most consistent loci of Republican support would appear to have been New England (and the Northeast more broadly), the Upper Midwest, and the Plains West. Only TR and Harding carried an interior Mountain West state by better than 2:1 (Hoover carried Washington State by better than 2:1). TR carried Idaho and Wyoming by better than 2:1 (along with all the Pacific coast states), and Harding carried Wyoming by better than 2:1 (along with California).

I'm not sure if there was anything in particular behind Wyoming's being the only interior Mountain West state to vote Republican by better than 2:1 more than once before the 1970s. It was the only interior Mountain West state to give Bryan less than 75% of the vote in 1896 (and it gave him much less than 75%--51.49%). It does make Wyoming the oldest > 2:1 Republican state to have voted Republican by better than 2:1 in the most recent election, but whatever made it so staunchly Republican in those two earlier elections lay in abeyance in the Eisenhower years, as Eisenhower never carried any Mountain West state by better than 2:1. 

In 1972, the outlines of a somewhat readjusted GOP base was evident; Nixon carried four interior Mountain West states by better than 2:1 (more than any previous Republican), but none in the Midwest or the Northeast. (He also carried most of the South by better than 2:1, but this was largely a one-off.) In 1980, Reagan won four interior Mountain West states by better than 2:1--the same as Nixon had carried in 1972 (Arizona, Utah, Idaho, and Wyoming) plus Nevada. Outside two Haga stack states, these were the only states Reagan won by better than 2:1 and with over 60% in 1980. In 1984, he carried the same five interior Mountain West states by better than 2:1, plus Alaska. The only states outside the interior Mountain West/Alaska that Reagan carried by better than 2:1 in 1984 were some Haga stack states, and New Hampshire, voting Republican by better than 2:1 for the first time since 1896. (Well, it had voted for Reagan by better than 2:1 in 1980, but with 'only' a 57.74% vote share.) New Hampshire had become an odd geographic outlier as a strong Republican base state outside the main regions of Republican strength--despite that its two neighbours, Vermont and Maine, had had much deeper histories of being Republican bastions. In his decisive 1988 win, the only state George H. W. Bush carried by better than 2:1 was Utah.

The next election in which a Republican would carry any state by better than 2:1 was 2000, when George W. Bush carried Wyoming, Utah, and Idaho by better than 2:1. (He also carried Alaska by better than 2:1, but with less than 60%.) These were all interior Mountain West states (and Alaska has typically behaved like an interior Mountain West state politically, if one wants to count it). Meanwhile, Bush carried none of the Haga stack states by better than 2:1. A Republican had never carried a Mountain West state by better than 2:1 without carrying any of the Plains states by better than 2:1 as well. It was 'only' Idaho's fifth, Wyoming's sixth, and Utah's fifth time voting Republican by better than 2:1 (whereas, if they had voted for Bush by better than 2:1, it would have been Nebraska's eighth time, and Kansas' twelfth).

In 2004, Bush once again carried Idaho, Wyoming, and Utah by better than 2:1, plus, this time, Nebraska (although not Kansas, as Douglas County not only voted Democratic for only the fifth time ever [after 1964, 1992, 1996, and 2000], but gave the Democrat a majority [and a landslide majority at that, of 57.1%] for only the second time ever, after 1964). This was, however, to be the last time a Republican carried Nebraska by better than 2:1. 

2012 represented a slight transition to a slightly different core Republican base in the Trump years. Romney carried three states by better than 2:1. Two were traditional Republican > 2:1 states in the Mountain West: Utah and Wyoming. The third, however, was Oklahoma. This was only the second time, after 2000, that the Republican carried a Mountain West state by better than 2:1 while not carrying any of the free-soil Plains states (Kansas, Nebraska, and the Dakotas) by better than 2:1 as well.

2012 was only the third time Oklahoma had voted Republican by better than 2:1, after 1972 and 1984. Counting Oklahoma as a Southern state, it was the first time since 1984 that the Republican had carried a Southern state by better than 2:1. 

In hindsight, it seems it should have seemed strange that Romney, a fairly traditional Republican, fell short of carrying Idaho and Nebraska by better than 2:1, while at the same time carrying Oklahoma by better than 2:1. 

In 2016, Trump carried four states by better than 2:1 and with over 60%, and he carried the same four by better than 2:1 again in 2020. This was the same number of states as Bush carried by better than 2:1 in 2004, but there was only one overlapping state: Wyoming. Aside from Wyoming, Trump's four > 2:1 states were a somewhat odd collection of states, not particularly amenable to being said to represent strength in a particular region. Wyoming was the only one in the Mountain West. It was also the only one that had voted for Reagan twice by better than 2:1. 

Another one, North Dakota, was a free-soil Plains West state, and had a history of having voted Republican by better than 2:1 several times--but it had never been the only one of Kansas, Nebraska, and the Dakotas to vote Republican by better than 2:1. And, even since North Dakota statehood, it had voted Republican by better than 2:1 substantially fewer times than either Kansas or Nebraska.

Joining North Dakota at the other end of the 'Haga Stack', however, was Oklahoma--a state that, again, had voted Republican by better than 2:1 only twice before the 21st century.

The fourth was truly novel: West Virginia. Lincoln had carried West Virginia by better than 2:1 in 1864, but that was apparently one of a number of idiosyncrasies in the period during and just after the War of Sections, as that had been the last and only time the Mountain State had voted Republican by better than 2:1 until 2016. 

None of these four bordered any of the others. 

To someone familiar with the concept of 'Greater Appalachia', Oklahoma and West Virginia would be apparent as 'Greater Appalachia' states. However, so is Kentucky. (And--unlike Tennessee and Arkansas--Kentucky, like Oklahoma, has no remaining blue counties casting fewer than 10,000 votes, implying that both are states into which the Black Belt does not extend.) And that does not explain North Dakota's appearance (after not having voted for Bush or Romney by better than 2:1) even at the same time as Nebraska has fallen off the list, or the persistence of Wyoming's overwhelming red status even as Idaho has become (slightly) less overwhelmingly red. 

Leaving Oklahoma aside, the other three do have something in common: a very low population. West Virginia was the only Greater Appalachia state that cast fewer than 1 million votes in 2020. North Dakota was the least vote-casting of the free-soil Plains states, casting less than 2/5 as much vote as Nebraska and less than 1/3 as much vote as Kansas. Wyoming was the least vote-casting state overall, casting less than 1/3 as much vote as Idaho. 

These are the percentages of the national vote cast by the > 2:1 Republican states in the past six elections:

2000
Utah: 0.73%
Idaho: 0.48%
Wyoming: 0.21%
Total: 1.41%

2004
Utah: 0.76%
Nebraska: 0.64%
Idaho: 0.49%
Wyoming: 0.20%
Total: 2.08%

2012
Oklahoma: 1.03%
Utah: 0.79%
Wyoming: 0.19%
Total: 2.02%

2016
Oklahoma: 1.06%
West Virginia: 0.52%
North Dakota: 0.25%
Wyoming: 0.19%
Total: 2.03%

2020
Oklahoma: 0.99%
West Virginia: 0.50%
North Dakota: 0.23%
Wyoming: 0.17%
Total: 1.89% 

Now, Oklahoma formed a larger share of the national vote in the last three elections, than any of Bush's > 2:1 states ever did in either 2000 or 2004. However, out of Trump's four > 2:1 states, Oklahoma and West Virginia are part of a newer Republican base area (Greater Appalachia). And even with Oklahoma, Trump's > 2:1 states never collectively exceeded the share of the national vote that Bush's > 2:1 states in 2004 accounted for. 

However, looking at individual states, it is noteworthy that two of Trump's > 2:1 states (North Dakota and Wyoming) each accounted for a substantially smaller share of the national vote than Bush's second-smallest > 2:1 state in either 2000 or 2004 (which was Idaho both times). 

For comparison, here are the shares of the national vote that Nebraska, Idaho, and Utah accounted for in 2016 and 2020:

2016
Utah: 0.83%
Nebraska: 0.62%
Idaho: 0.51%

2020
Utah: 0.94%
Nebraska: 0.60%
Idaho: 0.55%

In this light, the observation that 'with Omaha trending blue', Nebraska was 'not likely to return to' being 'among the brightest red states', together with the observation that the Dakotas 'prior to 2000 had a decent array of counties that leaned blue', might explain the changes in the Plains and Mountain West in terms of the > 2:1 Republican states. There are fewer and fewer states in which Democrats carry 'a decent array of counties'. However, population centres are, almost across-the-board, turning bluer or less red. Douglas County, Nebraska (home of Omaha) voted over 55% for Bush twice--while it was less red than the state both times, it wasn't the deadweight on the Republican vote share that it has become from 2008 on. Even though Romney carried the county, he did so by only 3.1%. Trump lost the county twice, by double digits in 2020.

Likewise, as Kevin Richert observed after the 2020 election, 

Ada County continued its shift from red to purple. While Trump carried Idaho by 30.8 percentage points, he won Ada County by only 3.9 percentage points. What’s more, Ada County’s presidential numbers have narrowed considerably; only 20 years ago, George W. Bush captured the county by 27.9 percentage points.

However, North Dakota has no county that cast even a third as much vote as Douglas County, Nebraska (and Wyoming has no county that cast even a fifth as much vote as Ada County, Idaho). Wyoming's largest county, Laramie County, was Biden's third-best county in Wyoming--but it is not remotely in danger of becoming a Maricopa or a Clark County, as Trump got 62% in it. He carried Cass County (North Dakota's largest county) only narrowly and with a plurality, but that is, of course, a better performance than he put in in Douglas County, Nebraska--added to which, he ate up all those 'prairie populist' counties that Democrats used to frequently carry before 2000 (and did not do terribly in when they did not carry them). In formerly strongly Democratic-leaning Mountrail County (which voted for Obama in 2008, and which Bush never carried by more than 8%), he exceeded 2/3 of the vote in 2020. Added to which, in North Dakota's second-largest county, Burleigh County--which cast about as much vote as Laramie County, Wyoming--Trump also got over 2/3 of the vote. (There is no similarly-sized county in Nebraska, but if there were, it would not account for as great a share of Nebraska's total vote as Burleigh does of North Dakota's. Trump did get nearly 2/3 of the vote in Hall County, Nebraska's fourth-largest county after Douglas, Lancaster, and Sarpy.)

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As pointed out above, after 1836, no state voted Democratic by better than 2:1 outside the South again until 1964, apart from 1896, 1932, and 1936. 

There was a high degree of overlap in the non-Southern states that voted Democratic by better than 2:1 outside the South in these three elections:

Arizona: 1932, 1936 (not a state in 1896)
California: 1936
Colorado: 1896
Idaho: 1896
Montana: 1896, 1936
Nevada: 1896, 1932, 1936
North Dakota: 1932
Oregon: 1936
Utah: 1896, 1936
Washington: 1936
Wisconsin: 1932, 1936

Of these 11 states, three (Montana, Nevada, and Utah) voted Democratic by better than 2:1 both in 1896 and at least once for FDR. All three are in the interior Mountain West. Another, Arizona, was not a state in 1896. 

Of the other seven, two (Idaho and Washington) voted for Bryan in 1896 (whether by better than 2:1 or not) and for FDR and Truman in all five of their elections (whether by better than 2:1 or not). They are also in the Mountain West, although Washington is also a coastal state. 

California and Oregon were extremely close in 1896, and both voted for FDR all four times he ran. (Oregon voted for Dewey in 1948.) Again, both are in the Mountain West.

That leaves Colorado, North Dakota, and Wisconsin. Colorado underwent an odd political evolution; it was Wilson's best state outside the South in 1916, but not only did it never vote for FDR by better than 2:1, but it voted for his Republican opponent in 1940 and 1944.

North Dakota was the only Plains State not seduced by Bryanism in 1896, but it did vote (narrowly) for Wilson in 1916. It was the only Plains State that ever voted for FDR by better than 2:1, and it did so only in 1932, not in 1936. (At least, not whilst also giving FDR more than 60% of the vote--Lemke did very well in North Dakota.) North Dakota went on to vote for Willkie and Dewey twice.

Wisconsin is perhaps the oddest state in this collection. It is not remotely in the West; it didn't vote for Bryan; and it voted for Hughes over Wilson in 1916 (the only state, other than Oregon, to have done so). But unlike Oregon, it was not particularly close in 1896, voting for McKinley by over 20%. Not only that, but, also unlike Oregon, Wisconsin was part of that clump of Upper Midwest states that voted for both TR in 1904 and Harding in 1920 by better than 2:1. 

One might have expected Minnesota to be more likely than Wisconsin to be a > 2:1 state for FDR in the Midwest at some point. Since 1932, Minnesota has been, along with West Virginia (but for a longer duration than West Virginia), one of the most consistently Democratic-leaning rural states. (Of course, it has a large city, but its Democratic lean, at least historically, largely rested on the Democratic lean of many of its rural areas. Kennedy narrowly carried it in 1960 despite losing Hennepin County outright. As Michael Barone pointed out in 2017, the only 'counties with heavy populations of blue collar workers' in which Hillary Clinton had carried 'white pluralities' were 'in northern Minnesota and Wisconsin, around Duluth and the Iron Range'.) Minnesota voted for FDR and Truman all five times, whereas Wisconsin voted for Willkie in 1940 and Dewey in 1944. Wisconsin also went on to vote for Nixon in 1960 and Nixon in 1968, whereas Minnesota voted for the Democrat in both elections. (Minnesota was also an exceedingly close state in 1916, whereas Hughes won Wisconsin by over 6%--Wilson would have been the first Democrat ever to carry Minnesota, had he carried it that year.) Minnesota came very close in 1936, but Wisconsin not only came close but did vote for FDR by better than 2:1--twice. 

In 1964, Johnson won a national landslide, and won eight states by better than 2:1. Not one of these states was a state FDR--or indeed any Democrat--had ever won by better than 2:1. This is a degree of lack of continuity not seen in the Republican Party. 

In fact, there is significant overlap between the states FDR won by better than 2:1 in his two landslides, and the states Nixon won in 1972 and Reagan won in 1984 by better than 2:1. 

The states Johnson won by better than 2:1 do have some interesting overlap with some other groups of states, however. Three of them were amongst the five states McKinley won by better than 2:1 in 1896. Three of them (the same three--Maine, Massachusetts, and Rhode Island) were amongst the seven states Grant won by better than 2:1 in 1872. Two of them (Maine and Massachusetts) were amongst the three states that Lincoln won by better than 2:1 in 1860. And three of them (Massachusetts, Rhode Island, and Connecticut) were amongst the four states John Quincy Adams carried by better than 2:1 in 1828. 

The states that Johnson won by better than 2:1 are a good predictor of whether those states would go on to vote Democratic. Only one has gone on to be solidly red: West Virginia. Six of the eight voted for Hillary Clinton in 2016. (The one that voted for Trump, other than West Virginia, was Michigan.) 

They were also a fairly good predictor of the states that have gone on to vote Democratic by better than 2:1 in subsequent elections. Rhode Island in 1968, Massachusetts in 1996, Hawaii in 2008, 2012, and 2016, and Massachusetts in 2020--all of these were amongst the states Johnson won by better than 2:1 in 1964. (Conversely, no Democrat has carried any of the non-Southern states FDR carried by better than 2:1 in either 1932 or 1936, by better than 2:1 in any election since FDR.)

There are three exceptions: Vermont, which voted Democratic by better than 2:1 in 2008, 2012, and 2020; Maryland, which voted Democratic by better than 2:1 in 2020; and Georgia, which voted Democratic by better than 2:1 in 1976. Georgia put on display Carter's incredible ability to roll the clock back, if only for one election. Georgia had been a > 2:1 Democratic state in many elections before 1960, of course, like most former Confederate states; but more notably, it had been one of only three states to vote for Truman by better than 2:1, and it was the only state to vote for Stevenson by better than 2:1 (and with over 60% of the vote), which it did in both 1952 and 1956. For some reason, it seems to have been slower to rupture with the Democracy than other Deep South states. 

One might think that Vermont's deep traditional Republicanism held it back from being a strong Johnson state in 1964. In fact, Vermont came very close to voting for Johnson by better than 2:1, and was easily more Democratic than the nation. However, it was markedly less Democratic than Massachusetts, Rhode Island, or Hawaii, all of which voted for Johnson by better than 3:1.

Vermont voted for John Quincy Adams in 1828, Lincoln in 1860, Grant in 1872, and McKinley in 1896 by better than 2:1. It was the only state that voted for Quincy Adams in 1828 or for Lincoln in 1860 by better than 2:1 that did not vote for Johnson by better than 2:1. One could say that Vermont's becoming a > 2:1 Democratic state on what seems likely to be a consistent basis completes the switch between the parties' bases. By winning Massachusetts and Vermont by better than 2:1, Biden won both states by better than 2:1, that Frémont had won by better than 2:1 in 1856. 

As for Maryland, Maryland hasn't much of a history of voting for anyone by better than 2:1. The last time it did so before 2020 was 1868, for Seymour.

It is somewhat interesting that Obama never carried Massachusetts by better than 2:1. This was the only state that Clinton carried by better than 2:1 in either of his elections (with over 60% of the vote). While Obama carried two states by better than 2:1 that no Democrat apart from Johnson had ever done (or, in one case, that no Democrat full stop had ever done), he failed to carry Massachusetts by better than 2:1, which might have seemed to mark a long-term drift by Massachusetts away from at least its previous level of Democraticness. But then, of course, in 2020, Biden carried Massachusetts by better than 2:1. I'm not sure what explains the Massachusetts hiatus during the Obama years. It's easy to explain in 2012 (when the state's former governor was the Republican presidential nominee), but not in 2008. 

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Elections in which some states were > 2:1 states

Alaska: 1984 (Reagan)
Arizona: 1932, 1936, 1972, 1980, 1984 (Roosevelt, Nixon, Reagan)
Hawaii: 1964, 2008, 2012, 2016 (Johnson, Obama, Hillary Clinton)
Idaho: 1896, 1904, 1972, 1980, 1984, 2000, 2004 (Bryan, Roosevelt, Nixon, Reagan, George W. Bush)
Iowa: 1904, 1920 (Roosevelt, Harding)
Kansas: 1864, 1868, 1872, 1876, 1880, 1904, 1924, 1928, 1952, 1972, 1984 (Lincoln, Grant, Hayes, Garfield, Roosevelt, Coolidge, Hoover, Eisenhower, Nixon, Reagan)
Maine: 1860, 1872, 1896, 1904, 1920, 1924, 1928, 1956, 1964 (Lincoln, Grant, McKinley, Roosevelt, Harding, Coolidge, Hoover, Eisenhower, Johnson)
Maryland: 1868, 2020 (Seymour, Biden)
Massachusetts: 1856, 1860, 1864, 1868, 1872, 1896, 1920, 1924, 1964, 1996, 2020 (Frémont, Lincoln, Grant, McKinley, Harding, Coolidge, Johnson, Clinton, Biden)
Michigan: 1904, 1920, 1924, 1928, 1964 (Roosevelt, Harding, Coolidge, Hoover, Johnson)
Minnesota: 1904, 1920 (Roosevelt, Harding)
Montana: 1896, 1936 (Bryan, Roosevelt)
Nebraska: 1872, 1904, 1920, 1952, 1972, 1980, 1984, 2004 (Grant, Roosevelt, Harding, Eisenhower, Nixon, Reagan, George W. Bush)
Nevada: 1896, 1932, 1936, 1980, 1984 (Bryan, Roosevelt, Reagan)
New Hampshire: 1836, 1896, 1984 (van Buren, McKinley, Reagan)
North Dakota: 1904, 1920, 1932, 1952, 1980, 2016, 2020 (Roosevelt, Harding, Roosevelt, Eisenhower, Reagan, Trump)
Oklahoma: 1932, 1936, 1972, 1984, 2012, 2016, 2020 (Roosevelt, Nixon, Reagan, Romney, Trump)
Pennsylvania: 1904, 1920, 1924 (Roosevelt, Harding, Coolidge)
Rhode Island: 1872, 1896, 1964, 1968 (Grant, McKinley, Johnson, Humphrey)
South Dakota: 1904, 1920, 1952 (Roosevelt, Harding, Eisenhower)
Utah: 1896, 1936, 1972, 1980, 1984, 1988, 2000, 2004, 2012 (Bryan, Roosevelt, Nixon, Reagan, George H. W. Bush, George W. Bush, Romney)
Vermont: 1856, 1860, 1864, 1868, 1872, 1876, 1880, 1884, 1888, 1892, 1896, 1900, 1904, 1908, 1920, 1924, 1928, 1952, 1956, 2008, 2012, 2020 (Frémont, Lincoln, Grant, Hayes, Garfield, Blaine, Harrison, McKinley, Roosevelt, Taft, Harding, Coolidge, Hoover, Eisenhower, Obama, Biden)
West Virginia: 1864, 1964, 2016, 2020 (Lincoln, Johnson, Trump)
Wisconsin: 1904, 1920, 1932, 1936 (Roosevelt, Harding, Roosevelt)
Wyoming: 1904, 1920, 1972, 1980, 1984, 2000, 2004, 2012, 2016, 2020 (Roosevelt, Harding, Nixon, Reagan, George W. Bush, Romney, Trump)