The asymmetry of US politics
Vox recently had a good video talking about “asymmetrical polarization”. Basically, this means that the two political parties in the US are moving further apart, and this is mostly driven by the Republican party, rather than the Democrats.
There are many aspects to this argument. Republicans have been more obstructionist than democrats, less likely to negotiate or compromise, and more likely to use filibusters. Their agenda has become more extreme over time. Democrats have also moved further left (despite complaints hereabouts that Democrats are too moderate), but in a way that trails the motion of the Republican party.
These many arguments stand on their own. But I want to address the very first argument that Vox presents, which comes from the following graph: