The roots of my theory of Affordable Family Formation influencing which states are blue and which are red in elections goes back to before the 2000 election, but it emerged in mature form in the weeks and months following the 2004 election. (Here's my 12/20/2004 American Conservative article Baby Gap and my subsequent 12/12/2004 VDARE article extending the correlation from fertility to years married. Here's a brief summary in 2005, and a fuller treatment in 2008.
Among academics, Andrew Gelman of Columbia has shown some kind interest in my theory. Now a Poli Sci Ph.D. candidate at the U. of Houston has tested my theory and published a paper on it. While I looked at state level voting for 2000 and 2004, George Hawley looked at county level voting in 2000 and Census data from 2000. This gives him a much larger sample size. The correlations I found at the state level in 2000 and 2004 were just ridiculously high, so looking at a bigger sample size of county data gives a broader perspective.
From Party Politics:
Home affordability, female marriage rates and vote choice in the 2000 US presidential election: Evidence from US countiesGeorge HawleyUniversity of Houston
This article tests the hypothesis that differences in the housing market can partially explain why some American counties are strongly Republican and others strongly Democratic, and that this phenomenon can be largely attributed to the relationship between home values and marriage rates within counties. Specifically, I test the hypothesis that, in the 2000 election, George W. Bush did comparatively better in counties with relatively affordable single-family homes, even when controlling for other economic, demographic and regional variables. Using county-level data, I test this hypothesis using spatial-lag regression models, and provide further evidence using individual-level survey data. My results indicate a statistically significant relationship between Bush’s percentage of the vote at the county level and the median value of owner-occupied homes, and that at least part of this is explained by the relationship between home values and marriage rates among young women.
Two important developments in American politics in recent decades involve political sorting. In a process that began in the 1970s, political conservatives and liberals have, for the most part, joined the Republican and Democratic Parties, respectively, which, many scholars argue, subsequently led to increasing ideological homogeneity within the parties and higher levels of partisan polarization. The other major sort is geographic in nature. Many regions of the country have become, to a significant extent, politically homogeneous, with an increasing number of counties consistently giving landslide victories to presidential candidates of one major political party or the other. The first major political sort – which led most individuals to align with the ‘correct’ political party based on their ideological inclinations – has been well examined and explained. The latter political sort has also been well described. However, up to this point, relatively little scholarship has examined the causal mechanism driving the geographic sorting of the population by partisan affiliation. Why do some regions prove a magnet for Democrats, and some draw increasing numbers of Republicans? ...
Specifically, I test the hypothesis that relatively affordable housing was associated with more support for George W. Bush in the 2000 election at the county level. Although the relationship between home-ownership and partisanship has been examined previously (Blum and Kingston, 1984; Verberg, 2000), most such studies consider home-ownership primarily as it relates to economic well-being or incorporation into the community. I offer an alternative hypothesis. I hypothesize that home affordability at the aggregate level is relevant to political outcomes even when controlling for economic variables such as median income and poverty rates. I argue that home affordability is relevant to politics largely because of its relationship with marriage rates within geographic units, which subsequently influences political outcomes because of the partisan marriage gap.
Put less abstractly, I suggest that married couples are more likely than single individuals to want to own their own home. However, there are some areas where home-ownership is prohibitively expensive, especially for younger Americans. If young couples living in those high-housing-cost communities want to own their own house, they have no choice but to move. Thus, I anticipate that the marriage rates within a county can be at least partially explained by the average housing costs within that county. Because, as the political science literature suggests, married voters are more likely to vote Republican than non-married voters, this trend leads some counties to become increasingly Republican, and others increasingly Democratic. ...
The possible relationship between home affordability and aggregate voting trends has largely been ignored up until now by the political science literature, though the topic has been considered by the political journalist Steven Sailer (2008). Sailer hypothesized that ‘affordable family formation’ – which he argued was closely related to housing costs – was a key difference between majority-Republican states and majority-Democrat states. Sailer went on to conclude that the relative affordability of housing accounted for the differing typical political behaviour within various large cities. Sailer suggested that the relative costliness of owning a home in America’s large coastal cities, such as Los Angeles, led to later family formation, which partially explained the greater support for Democratic politicians in those cities and regions. In contrast, inland American cities like Dallas are able to expand outward all-but indefinitely, which keeps housing costs low and subsequently such cities more attractive to young families. ...
This article suggests that the geographical sorting of the United States along partisan lines results, at least in part, from differences in housing markets. Specifically, these results indicate that, in the 2000 presidential election, George W. Bush typically received a smaller share of the vote in counties where home values significantly outpaced incomes, and that this was, to a meaningful extent, due to the relationship between home affordability and marriage rates.
Hawley could likely replicate this finding for 2004, an election that was virtually identical to 2000, just shifted a few points in Bush's direction. 2008 was not as similar, however, in part because of different turnout rates brought about by Obama's candidacy. 2010 looked a lot like 2004, although there are methodological problems with dealing with midterm elections.