Deadlock and Partisan Bitterness

Why does American politics seem so deadlocked?  The media mostly focuses on issues where Democrats and Republicans refuse to compromise because they strongly disagree: immigration, guns, health care.  But American politics often seems deadlocked even when both parties agree.  For example, supermajorities of both parties want to protect DREAMers, but they’ve never reached an agreement to do so.  How is this possible?

1. Transactions costs.  Hammering out a deal is hard work, so many mutually b...