Here's an interesting paper by Edward Glaeser and Bryce Ward on myths and realities regarding changing political geography over time in the U.S. and the validity of the "red state/blue state" paradigm:
Myths and Realities of American Political Geography, by Edward L. Glaeser and Bryce A. Ward, NBER WP No. 11857, December 2005 [free link to paper] Introduction In the aftermath of the 2000 election, David Brooks wrote in the Atlantic Monthly that America was split into red states and blue states. In red states, people believed in God, watched NASCAR and voted for George W. Bush. In blue states, people ate Thai food, cared about the environment and voted for Albert Gore. The 2004 election, which seemed geographically to be a replay of 2000, only reinforced the perceived value of this framework. Only three states (Iowa, New Hampshire and New Mexico) switched parties between the elections.
In this essay, we revisit America’s political geography and ask what is true and false about the “red state/blue state” framework. We begin by identifying five myths associated with this framework: 1) America is divided into two politically homogenous regions; 2) The two parties are more spatially segregated than in the past; 3) America’s political geography is more stable than in the past; 4) America’s cultural divisions are increasing and 5) America is becoming more politically polarized.
But despite the myths surrounding the red state/blue state paradigm, there are two important truths captured by this framework. America is a country with remarkable geographic diversity in its habits and beliefs. People in different states have wildly different views about religion, homosexuality, AIDS, military policy and wildly different consumption patterns. The distribution of states along all dimensions is continuous, not bimodal.... Moreover, America’s ideological diversity is not particularly new. ... The extent and permanence of cultural divisions across space is one of America’s most remarkable features. While spatial sorting on the basis of income or tastes may seem natural to most economists, the remarkable spatial heterogeneity of beliefs – political and otherwise – presents more of a challenge to the standard Bayesian models of belief formation. For example, in the April 2004, CBS/New York Times poll, twenty-three percent of respondents in Oregon, Washington and California thought that Saddam Hussein was personally involved in the September 11, 2001, attacks. Forty-seven percent of respondents in Texas, Oklahoma and Arkansas had that view. In the 1987-2003 PEW Values surveys, 56 percent of Mississippi residents think that AIDS is God’s punishment for immoral sexual behavior. Only 16 percent of Rhode Island residents share that view.
Using state and county level regressions, we explore a number of different hypotheses about the long run historical causes of differences in beliefs over space. We find little support these cultural differences represent long-standing differences in religiosity or the legacy of slavery.
Instead, our regressions support the idea that Blue State culture reflects primarily the legacy of different ethnicities working together at high densities: the most important historical explanatory variables are the share of the labor force in manufacturing in 1920 and the share of the population that was foreign born in 1920 strongly predict liberal beliefs and voting for John Kerry. ...
The second important truth captured by the red state/blue state framework is that political parties and politicians have had an increasing tendency to divide on cultural and religious issues rather than on economic differences. Again, in historical perspective, cultural politics is not unusual. In the late 19th century, “Rum, Romanism and rebellion” were the core issues that determined the Republican Party. The true aberration was the midtwentieth century era of economic politics...
Here are a few graphs and tables from the paper (click on figures for larger pop-ups):