So I have been reading up on the polarization of american politics and the loss of the political center. From what I can tell the shift happened in the late 60's and 70's. Essentially people started sorting themselves geographically, the northeast became more homogenized as a liberal bastion and the south lost most of its Democrat representatives as liberals and conservatives sorted themselves geographically. This resulted in the Senate and house becoming more polarized as it became harder for centrist candidates to gain coalitions and win elections.
Why? What about the 70's made us more mobile/willing to move to places where people believe what we believe? Or am I completely off base here?
Well, you're not off base, and there are a lot of factors, but I'd focus on race first.
When LBJ signed the Civil Rights Act in 1964, apparently he told one of his press secretaries that the Democrats Lost the South for a generation. While other sources question the validity of this quote, President Obama thinks Johnson said this.
While subsequent presidential elections have proved that party untrue (Carter, Clinton and Obama won southern states), I think with the House and Senate, you might be onto something.
I recently finished this book and wrote a piece where I was focusing on white ethnic voters during this time period and into today.
Here's a quote from Richard Wirthlin, Ronald Reagan’s campaign pollster in June 1980:
The forces for victory could be found in the votes of "Southern white protestants, blue collar workers in the industrial states, urban ethnics, and rural voters” — that is, the old working-class constituents of the Democratic Party. . . Working Americans, he argued in echoes of Nixon, are “no longer solely motivated by economic concerns but by larger social issues as well."
Now I've just focused on the south, but I think you might also look at these social issues that the Reagan championed in the decade after, the 1980s.
I also think 9/11 sharpened the divide, and maybe that also goes into religion, but at least today, besides race, I see the divides as partially religious and partially cultural.
Source: Cowie, Jefferson. Stayin’ Alive: The 1970s and the Last Days of the Working Class, The New Press, 2012.