AlexS
Nomad
Looks like around a quarter of the people showed up for Trump's inauguration. That's OK though.
DC voted 91% Democrat in the 2016 general election. It voted 92.5% Democrat in 2008. Plus, DC population is about 50% black, so the election and inauguration of the first black president was a special emotional event for a lot of that population (and many other people, given America's history). Makes sense that a lot fewer people would turn out for the inauguration of a Republican president, especially one who was so thoroughly demonized on racial grounds.
As for out of towners, I would speculate that this inauguration's lesser historical significance wasn't such an attraction, and the possibility of major protests kept away some who might otherwise want to travel into DC for the event.