US election 2016: Divided nation split into 'alien tribes'
22 February 2016 Last updated at 09:35 GMT
More like "alien tribes" than rival parties. That's how the Pew Research Center describes how the two sides in an increasingly divided America see each other.
They can't stand the other side's viewpoint - and because hyper-partisan news and social media enables them to live in ideological isolation - they don't even have to try to understand it.
The BBC's Franz Strasser looks at the demographic trends that have made the US increasingly divided.
Join the debate over divided America at bbc.com/US2016live.