Density

When I read in the New York Times Magazine that Los Angeles was more dense than New York, I was astonished. How could this possibly be true?

The factoid came from a sidebar (page 80 of the June 8 issue) listing the cities with the highest population density:

Mumbai: 76,790 people/sq. mile
Calcutta: 61,945 people/sq. mile
Karachi: 49,000 people/sq. mile
Lagos: 47,027 people/sq. mile
Shenzhen: 44,463 people/sq. mile

Under the list, it said the following: By comparison, L.A. is No. 90 on the list, with 7,068 people per square mile; New York is No. 114, with 5,309.

This makes no sense. New York is known for its density and L.A. for its sprawl. Livable Places.org cleared it up for me:

In “L.A. the King of Sprawl, Not at All,” (LA Times, 10/23/05) Robert Bruegmann reports that according to the U.S. Census Los Angeles is the densest urbanized area in the country. The U.S. Census defines an urbanized area as “core census block groups or blocks that have a population density of at least 1,000 people per square mile and surrounding census blocks that have an overall density of at least 500 people per square mile.”(www.census.gov) This isn’t urban in the sense of a city, but rather urban in the sense that it is not farmland, open space or wilderness.

The “urbanized area of New York” by this definition is roughly the NE Corridor which includes 28 different counties in 3 different states; it is home to 18 million people and has a population density of approximately 5,000 people per square mile. The “urbanized area of Los Angeles” has 12 million people and includes five different counties; it has a population density of approximately 7,000 people per square mile. Though it is true that the urbanized area of Los Angeles has a greater population density than the urbanized area of New York City, the urbanized area of Los Angeles is half the size of New York City’s. The statistical trick that Bruegmann claims to be non-existent is indeed very present. If the urbanized area of Los Angeles was close to the size of that of New York we would begin to see a very different picture.

In other words, it's sneaky statistics. If you compare the wrong things, you'll get wildly different answers. Are we talking about housing density or population density? Where do you draw lines when defining urban areas?

The factoid comes from the City Mayors website. It lists the population of the New York urban area as 17,800,000 and the L.A. area as 11,789,000. But averaging out the density over these big areas doesn't make logical sense -- they are made up of too many different types of localities. Livable Places.org puts Manhattan's density at 66,900 and New York City's density at 26,400. The City of Los Angeles has 7,900 people per square mile and Los Angeles County has 2,344.

Other facts from the Times:

Fastest-Shrinking Cities in U.S.
By percentage change from April 200 to July 2006:
New Orleans: -53.9
Detroit: -8.4
Cleveland: -6.9
Pittsburgh: -6.5
Flint: -6.3

Largest Subway Network:
London (253.5 Miles)

City With the Most Subway Stations:
New York (468)

Largest Subway Loop:
Seoul (30 Miles)

Largest Metropolitan Areas in 1900:
London: 6.5 million
New York: 4.2 million
Paris: 3.3 million
Berlin: 2.7 million
Chicago: 1.7 million

Largest Metropolitan Areas in 2006:
Tokyo: 35,530,000
Mexico City: 19,240,000
Mumbai: 18,840,000
New York: 18,650,000
Sao Paulo: 18,610,000