Bill Bishop opens his book The Big Sort illustrating how counties have become more politically homogeneous. However, he points out that people generally didn’t choose to move where they did based on political criteria. They tended to move to places where they felt comfortable and their identity was reinforced. People with common lifestyles and identities tend to vote in similar ways. Therefore, even though choices were not political they had important political consequences.
Studying counties that had once been competitive voting districts, Bishop noticed an interesting pattern. Once a county began to tip one direction or the other, the rate of change seemed to accelerate. As homogeneity toward one view began to develop, seemingly people who shared emerging dominant view moved in and those with the minority view may have left.
Of particular interest is his observation that geography (i.e. where you live) matters more than other demographic data when it comes to predicting people's viewpoints. Bishop writes:
Regardless of demographic category – age, gender, religion, occupation – Pew found a difference in support for the war based on geography. Labor union members were against the war in Democratic counties but for it in Republican counties. (Nearly 30 percentage points separated union members in strong Democratic counties versus strong Republican counties.) Women were against the war in Democratic but for it in Republican counties (a difference of 23 percentage points.) The partisanship of place overpowered the categories that researcher normally use to describe durable voting blocks. (48)
Looking at the counties that had lopsided vote margins in 2004 and working backward over the past sixty years, Bishop wanted to know if anything else had changed about the demographics other than political preferences.
Education –Democratic landslide counties saw a disproportionate increase in the percentage of the population with a college degree or higher.
Religion – Republican landslide counties had above average increases in church membership.
Immigrants – In 2000, 21% of the population in Democratic landslide counties was foreign-born American versus 5% in Republican counties.
Race – The white population was nearly equally divided across the four county groups (Democrat competitive and non-competitive; Republican competitive and non-competitive) in 1970. By 2000, 30% of whites lived in Republican landslide counties and 18 percent lived in Democrat landslide counties.