Mechanisms of our current political polarization.

I want to point to three sources that provide complimentary perspectives on the origins and maintenance of the extreme Red versus Blue divide in the U.S.:

The first is a freakonomics podcast, with a text version also offered,  describing how Republicans and Democrats form a duopoly analogous to Coke and Pepsi, Intel and AMD, Boeing and Airbus, etc.

"America's Hidden Duopoly - We all know our political system is “broken” — but what if that’s not true? Some say the Republicans and Democrats constitute a wildly successful industry that has colluded to kill off competition, stifle reform, and drive the country apart.  So, what can we do about it?

A second perspective is offered by Yang et al., who provide a "Satisficing" Dynamical Model of why U.S. political parties are so polarized. Here is a summary by Clint Sprott of the Univ. of Wisc. Chaos and Complex Systems Discussion Group:

Basically, it contends that when the parties are too centrist and too inclusive, voters with extreme views find little reason to choose one over the other and either abstain from voting or vote randomly. Thus it is advantageous for the parties to move off center to pick up more of these voters. In the coming election, most people long ago decided which side they are on. Thus all the parties can hope to do at this point is to induce those who lean in their direction to get out and vote. Would mandatory voting reduce polarization? Why is the popular vote usually so close to 50/50?

And finally, a book by Achen and Bartels, "Democracy for Realists: Why Elections Do Not Produce Responsive Government." From the book description:

Democracy for Realists assails the romantic folk-theory at the heart of contemporary thinking about democratic politics and government, and offers a provocative alternative view grounded in the actual human nature of democratic citizens.

Christopher Achen and Larry Bartels deploy a wealth of social-scientific evidence, including ingenious original analyses of topics ranging from abortion politics and budget deficits to the Great Depression and shark attacks, to show that the familiar ideal of thoughtful citizens steering the ship of state from the voting booth is fundamentally misguided. They demonstrate that voters―even those who are well informed and politically engaged―mostly choose parties and candidates on the basis of social identities and partisan loyalties, not political issues. They also show that voters adjust their policy views and even their perceptions of basic matters of fact to match those loyalties. When parties are roughly evenly matched, elections often turn on irrelevant or misleading considerations such as economic spurts or downturns beyond the incumbents' control; the outcomes are essentially random. Thus, voters do not control the course of public policy, even indirectly.