From the Utne Reader, in an article showing that we ” are segregating [our]selves politically and geographically” in the U.S. :

“In 1992, 38 percent of Americans lived in counties decided by landslide elections; by 2004, that figure was 48 percent.”

One thing that jumps out at me immediately is that elections are very hard to compare to one another. In this case, 1992 represented the unseating of an incumbent in a three-way race (remember Perot?) — whereas 2004 was the two-way reaffirmation of an incumbent president with no real third party presence. 

How might this affect things? Well, let’s say we define a landslide as getting 60% or more of the vote. In a three way race (like 1992), that would be difficult. Clinton won the election with 43% of the vote (to Bush’s 38, and Perot’s 19). Assuming some deviation off of that average from county to county, you are still unlikely to get a 60% landslide — even a county 50% more Democratic than the average county is still barely breaking the landslide barrier (0.43 * 1.5 = 0.64).

In a two-way race the dynamics are different. In the Kerry/Bush 50/50 split, a candidate that wins in a 50% more Democratic county is going to win by 75%.

The second problem (which we ignored in the above calculation) is that counties are not a good unit of measurement. The majority of counties are small, Republican entities, even though voters are roughly split nationwide (Democrats live in more populous counties). I imagine too, that because the majority of counties are Republican that Republican wins will look polarizing (look at all those deep red counties!) whereas Democratic wins will look less polarizing (the counties that go dark blue will be fewer, but more populous, whereas the Dem votes will eat into the red counties). 

In any case, why not compare something more comparable — like 1984 and 2004? That has problems, but a whole lot less I think. Or compare mid-terms, where the national politics is less confounding.