Comment by russell

I'm not sure where you got your numbers. The 10 largest cities in the US have a population of 26M (2015 estimates, Wikipedia). Generally population estimates are given for the metropolitan area. The 10 largest have a population of 73 million. There are 53 MSAs with a population over 1M with perhaps a total population of 150M. (I was too lazy to do all the addition.) The US has a large area, but it is primarily urban.