Dividing population by total land area is a horribly misleading way to understand density. There are alternatives, like population-weighted density, that give you a better picture: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3119965 Here's a blog post where somebody re-invented the concept and analyzed density in Europe: https://theconversation.com/think-your-country-is-crowded-th...

The population-weighted density of the US is roughly similar to continental Europe.