Business Insider: This map shows the US really has 11 separate 'nations' with entirely different cultures
Washington Post: Listening allows people who are opponents to avoid becoming enemies.
538: Politics Is More Partisan Now, But It’s Not More Divisive
NYT: How Is the Economy Doing? It May Depend on Your Party, and $1
Washington Post: Obama is the most polarizing president on record
Medium: The "Other Side" Is Not Dumb
NYT: How Social Media Silences Debate
Pew: Political Polarization in the American Public
NYT: Bipartisanship Isn’t for Wimps, After All
NPR: Fear and Loathing across Party Lines: New Evidence on Group Polarization
University of California: When it comes to politics, you’re not as rational as you think
N&O: Leaders must engage in civil dialogue
Pew: Political Polarization & Media Habits