Kowloon Walled City in 1989, five years before it was demolished. |
According to some wonky urban geography experts, the answer is 65 million people. That's the number, at least, that Amy O'Leary reports in a fascinating New York Times article covering Manhattan's complex infrastructure, and forecasts about it.
That estimate is based on the area with the highest density ever measured, Kowloon Walled City, an ungoverned settlement in Hong Kong demolished in 1994. O'Leary writes that the district, originally a Chinese military fort, was about the size of five football fields and housed around 35,000 people at its peak in the 1980s.