[wahern]

The population-weighted density of the U.S. is approximately the same as Europe, especially Central and Northern Europe. Standard density, the measure which leads people to believe the U.S. to be sparsely populated, is a useless metric, only suitable for questions like how much uninhabited land exists per capita.

However, similar density (standard or population-weighted) alone doesn't automatically make public transit any more politically or socially viable. According to an early paper on COVID-19 death rates, population-weight density (but not standard density) could explain cross-country variance in the initial rate of spread of COVID-19, but not the subsequent evolution of the pandemic. https://arxiv.org/pdf/2005.01167.pdf For the latter, the researchers needed to turn to the Hofstede cross-cultural measure of individualism to explain country variance.

That points to the more likely reason the U.S. has trouble with public transit--not because we live sparsely (we don't), but because of our highly individualistic culture. IOW, we don't like it. Indeed, as COVID-19 has arguably shown, as compared to many other countries, we would literally prefer to die than to be more pro-social.