I highly recommend the following TED talk on the causes and consequences of contemporary political polarization by social psychologist Jonathan Haidt:
My only critique is that he puts a bit too much emphasis on and faith in the likelihood that a few institutional tweaks (like open primaries) will dramatically change the current state of partisan polarization. Most political science research has shown that the causes of polarization are wide and deep and likely won’t be reversed by looking only at institutional changes. (See here, here, and here.)
Other than that, I highly recommend this TED talk.