For the past two decades, the presidency and both houses of Congress have been hotly contested by the two major political parties. Yet, geographically, the United States seems to be increasingly marked by "red" areas where the Democratic Party lacks any ability to even dream of winning office and "blue" areas where the Republican Party lacks enough electoral support to produce viable candidates. There are two possible reasons America is more politically segregated than in the past. The first reason, argued by Bill Bishop (2008) in his book "The Big Sort," is that increasingly, people are choosing their neighborhoods based on criteria that correlate highly with political preferences. This argument suggests that political segregation is a product of the movement of voters between neighborhoods; as kids grow up and move out of their parents' homes, or people move from one home to another, they are choosing neighborhoods that contain more co-partisans. However, there is another possible reason for a more politically segregated America. The United States went through what political scientists call a "political realignment" in the lead-up to and following the Civil Rights Act that rocked what it meant, ideologically, to be a "Democrat" or a "Republican" (e.g., Schickler 2016). From the 1970s to the mid-1990s, journalists (e.g., Broder 1972) and academics (e.g., Wattenberg 1998) alike bemoaned the apparent meaninglessness of the two political parties. Using these two theories as a motivating force, the authors set out to examine the extent to which the United States has become more politically segregated and to see whether they could isolate which factors have contributed to this sorting.