The transformation of American political parties has largely been shaped by two significant factors: the enfranchisement of black voters and immigration. These developments have shifted voter demographics, with a notable increase in nonwhite support for the Democratic Party. In the 1950s, nonwhite voters accounted for a mere 7 percent of the Democratic electorate, but this figure surged to 44 percent by 2012, highlighting a substantial change in party affiliation among racial minorities.

Conversely, the Republican Party has maintained a predominantly white voter base, with almost 90 percent of its supporters being white well into the 2000s. This stark contrast illustrates a division in party alignment based on race, where the Democrats have embraced a more diverse coalition, while the Republicans have remained largely homogenous. This shift not only reshapes electoral strategies but also reflects the broader social dynamics impacting American politics.