As part of a look at the connection between education levels and car ownership, Derek Thompson includes this information about which American cities have lower rates of car ownership:

Here are the non-car household rates in 30 large U.S. cities (the national average is in RED):

What do NYC, DC, Boston, and Philadelphia have in common? For one, they’re old, crowded cities with good (okay, decent) public transit. “The five cities with the highest proportions of households without a vehicle were all among the top five cities in a recent ranking of the quality of public transportation,” Michael Sivak, director of Sustainable Worldwide Transportation at Michigan, told WSJ.

That might be the most important, variable, but it wasn’t the first thing this graph reminds me of. When I see New York, D.C., Boston, Philadelphia, San Francisco, the first thing I think is: These are all the classic, even cliche, magnets for elite college graduates. 

So I compared the cities’ non-car ownership rates to their share of bachelor’s-degree holders. And it turns out there is a statistically significant relationship between being college-dense and car-light.

Then follows a correlation chart – but no number or measure of the significance of the relationship! If one is going to claim a statistically significant relationship, more information needs to be provided like the correlation coefficient and the significance level.

That said, larger Sunbelt cities don’t come out well, nor do smaller Northern or Midwestern cities. All together, these cities are more likely to have sprawl and not have the kind of dense downtowns like Manhattan or the Loop that supports a lot of workers traveling to a single area each day. There was less historical incentive in these communities to build mass transit (outside of commuter rail) and such services, particularly subways or light rail, are quite expensive to build today in more sprawling conditions.