Theodore White noted the "deadly uniformity of returns in every region" of both those landslides; the same was true in '84.
That’s
not true of 1936: Landon held the rural Northeast very firmly, and also held Unionist parts of Appalachia and the Ozarks sufficiently that he exceeded his national vote share in Missouri, Kentucky and West Virginia (1936 was the last time West Virginia voted more Republican than the nation until 1972).
1984 was quite uniform across all regions – which is why Reagan was able to get close to a fifty-state sweep with a margin seven percentage points less than Harding in 1920. However, at the local level Mondale did hold the loyal majority-minority and then heavily unionized counties well – he only won his home state on majorities in St. Louis, Carlton and Lake Counties than were more than 20 percentage points above what McGovern managed. Moreover, as I have noted Nixon got up to 20 percent more than Reagan could in the South Texas Democratic bastion – in Jim Hogg County Nixon got 47 percent and Reagan less than 30 percent.
However, the combination of large-scale destruction of former party bastions, a huge popular vote victory, and massive coattails makes 1920 far more impressive than 1984. Tennessee not only voted for Harding, but even elected a Republican
Governor in Alfred A. Taylor – the last Republican Governor of any former Confederate state until after 1965. In contrast, as was normal during the dealignment era from 1950 to 1980, Reagan’s coattails were minimal, with a net gain of one Governor and farm-crisis-induced losses in North Dakota and Washington.