[Yuri]

Yes, Manhattan is below the peak, but their density is so high that's only natural. It's like Paris or specially Kowloon. For the island, yes, overcrowding was an issue on its "decline".

Other US cities, however, could comfortably house way more people without been specially dense. Of course, housing must be provided so indeed there will be pockets of overcrowding even in not so dense places.