Amy O’Leary, reporting for the New York Times:
Packing Manhattan as tightly as Kowloon Walled City, river to river, would mean jamming in 65 million people. That’s if every surface was built on. If the current streets and parks were left intact? About half that many, or nearly the population of California.
Kowloon Walled City in Hong Kong was a free-for-all warren of dystopian flats that packed 33,000 people into 6.5 acres. As O’Leary says, no one wants to live like that. But it’s still a fun thought exercise.