yet another way to look at density

Some commentators note that the Los Angeles metropolitan area has more people per square mile than other regions, and use this alleged fact as an argument why density doesn't affect a region's level of car dependency.  One region this argument is silly is that Los Angeles density is quite different from that of more transit-oriented cities.  The most transit-oriented cities (New York, Philadelphia, Boston, Washington, Chicago and San Francisco) have a core that is far more compact than their suburbs, while the city of Los Angeles is not significantly more dense than its suburbs.

Another way to compare densities is to look at comparable neighborhoods.  Are the inner neighborhoods of car-dependent cities as compact as those of transit-oriented cities?

Answer: no.  Let's start with Jacksonville (one of the most car-dependent cities in America, where less than 2 percent of city residents use public transit to get to work).  Two of Jacksonville's non-downtown core neighborhoods (that is, those closest to downtown) are San Marco in the south, Riverside in the west.  According to city-data.com, San Marco has only 2290 people per square mile. Riverside has 3505 people per square mile.

Similarly, in San Diego just under 4 percent of commuters use transit.  One of its near-downtown neighborhoods, Little Italy, has 5597 people per square mile- more than Jacksonville's more compact areas, but not much more. 

Los Angeles is slightly less car-dependent, with a transit market share of just over 10 percent for city residents (as opposed to suburbanites). One of its just-outside-downtown neighborhoods, Silver Lake, has 9858 people per square mile.

In Boston, about 1/3 of city commuters use transit.  Beacon Hill, an elite neighborhood just north of downtown, has 21,088 people per square mile.  Washington is about as transit-oriented as Boston, and one of its just-outside-downtown neighborhoods are Dupont Circle (17,252 per square mile) and 

And in New York, of course, transit usage is higher than in any of those cities- and the citywide density is higher than in any of the neighborhoods discussed above.  For example, Murray Hill is just east of midtown New York City- and it has 67,775 people per square mile, three and four times the density of Washington and Boston's comparable neighborhoods. 

Notice a pattern?

Of course, a more scientific survey would go through every neighborhood within a 2-mile radius of downtown.  But the above data should at least give you an idea of what distinguishes the most car-oriented cities from the least car-oriented cities.