how many cities have the density of san francisco and new york?
In addition, Los Angeles is number 87. The only other entry in North America is Toronto-Hamilton (#83).
The top 90 cities (i.e. up to and including New York City) have a combined population of 965 million.
Also note that smallest in the top 100 is 4.3 million, so this probably misses a lot of smaller but more dense cities.
https://en.wikipedia.org/wiki/List_of_urban_areas_by_populat...
You run into the same sorts of things with most cities. Urban density is at least somewhat a function of fairly arbitrary political boundaries.