It's really easy to forget how incredibly large a mile is. A single square mile is just under 28
million square feet. A population density of 742/sq mile means each person would have about 37,000 square feet to themselves. Not exactly a struggle for leg room.
Large scale population densities don't tell you anything, due to the fact that we have this habit of trying to fit as many of ourselves into the smallest places possible. San Francisco city, for instance, has a population density of 18,634/square mile. And while that's relatively dense it's dwarfed by places like Manila (Philippines) with a density > 111,000 per square mile. And if you want to go full on crazy there was Kowloon Walled City [1] in Hong Kong which had a population density in excess of 5,000,000 per square mile! That number's a bit misleading due to verticality, but not by much! That's probably the most densely packed area of a sizable population that there has ever been, and by a pretty wide margin.
[1] - https://en.wikipedia.org/wiki/Kowloon_Walled_City