Below are two population density maps of Manhattan. One is from 1910; the other 2010. The latter shows a city that’s absorbed the explosion in high-rise living and the growing desperation of pretty much everyone in the world to live on an island that isn’t getting any bigger (well, not much bigger, anyway).
The twist is, the diagram that best mirrors the skyscraper-littered shape of modern Manhattan actually shows the city at the beginning of the last century. Here are the same diagrams again:
Image: Schlomo Angel, Planet of Cities.
Over the past century, Manhattan’s population has actually fallen by a little under 25 per cent. To put it even more plainly:
This shrinkage tells a story of improved transport links and living conditions. In the early 20th century, many factory workers lived in packed tenement blocks, often with large families. These tenements clustered on the Lower East Side, where population density has now dropped from at least 1,200 people per hectare to 600 or fewer. The rich, meanwhile, employed fleets of servants, making the average household far larger than it is today.
Subway expansions, price rises and the razing of the city’s slums all helped push residents to other boroughs over the past century. As a result, far more people now work in Manhattan than live there. These density maps show the island’s current population densities by day and night:
Image: Joe Lertola, via Time Magazine.
As you can see, those red blocks don’t magically reappear in the visible portions of New Jersey or Brooklyn at the end of the working day – these city workers come from even further afield.
This ability to commute to the packed island, rather than attempting to live there, was massively boosted by the introduction of a subway system whose fares are part-publically subsidised. The first underground line opened in 1904. The network now covers pretty much the whole of New York City:
The island’s population recently began to rise again, so it remains to be seen which way the trend line will go. If flying cars take off, of course, no one will need to live on overpriced Manhattan real estate at all – it’ll just be a network of office blocks and landing strips.