[_delirium]

What's odd is that Manhattan's population density has on a long timescale been declining rather than growing, despite quite a bit of construction. In the 1900 census the population was 1.85 million (density ~80,000/sq mi), and it reached its peak of 2.33 million (~100,000/sq mi) in the 1910 census. Since then it's on the way down, with some bumps here and there: 1.96 million (~85,000/sq mi) in 1950, and all the way down to 1.54 million (~70,000/sq mi) by the 2000 census, having lost a full 1/3 of its population since 1910. The 2013 census estimate does put it at least on a growth trajectory again, to 1.63 million, but it'll be a while before it climbs up past 2 million again at that rate.

The main reasons, as far as I can gather, seem to be: 1) lower-class residential towers are being replaced by higher-end residential towers with larger units and fewer people per sq ft; 2) even given the same units, people are living fewer to a unit (fewer children, fewer multigeneration households); and 3) commercial real estate is crowding out residential real estate.

[dankohn1]

Here's a great illustration of the falling density in Manhattan from 1910 to today: http://www.vox.com/2014/9/23/6832975/manhattan-population-de...

[nostrademons]

Interesting...based on that illustration, it seems like #2 is the dominant factor. The areas of previously highest density are the Lower East Side and East Village, formerly working-class immigrant enclaves with more tenements than highrises.

[bradleyjg]

I don't know that Manhattan, either in the geographic sense or real estate broker sense, is a great unit of measure for urban planning / comparison purposes.

There are parts of even Manhattan south of 14th street that have longer commutes to Wall Street than parts of Brooklyn or Jersey City.

Yes, Manhattan doesn't contain very many high density lower-middle-class immigrant neighborhoods anymore, but NYC still very much does. I'm not sure which side of the river they are on matters much.

[ori_b]

I suspect that the actual density in terms of average people present per square km is increasing (as opposed to the number of people living there on paper). Especially during working hours.

Tons of people commute in. Competing with the businesses that use the space for commuters is expensive

[krschultz]

In terms of #3, anywhere developers can build residential, they will. Rents & prices on residential are much higher. Unfortunately Manhattan zoning prevents residential in large parts of the city. I believe that is why there are so many hotels going up in the 20s/30s on the west side, when that is someday rezoned it will be easier to convert to residential than offices would have been.

[akgerber]

The garment district (the 20s/30s on the West Side) is zoned industrial. Hotels are legal in industrial zones, but apartments aren't, so hotels get built.

[mc32]

That and overcrowded tenement buildings full of fire hazards going away helps push down density, but in this case for the better.