Mass Transit is Good for the Environment, Right?

Mass transit is good for the environment, right? Well, sometimes. Not always. In big cities, such as New York and Chicago, it helps to reduce the per capita carbon footprint. In smaller cities, such Pittsburg and Memphis, however, it often isn't because ridership is too low. Rather than reduce the per capita carbon footprint, it increases it. Thus, smaller cities that are thinking of building a mass transit system may want to think twice about it (if they care about the environment, that is), and those that already have one, need to explore ways to increase ridership.

This disturbing (but somewhat unsurprising) fact is covered in the latest Freakonomics podcast, "Mass Transit Hysteria." It is also covered in a Freakonomics blog post by Eric Morris ("Can Mass Transit Save the Environment? Right Wing or Left Wing, Here's a Post Everybody Can Hate."), a regular Freakonomics contributor, who is also featured in the podcast.