Source: U.S. Census Bureau American Community Survey, 2009. Data not available for the following metro areas: Charleston, W.V., Hickory-Lenoir-Morganon, N.C., and Kalamazoo-Portage, Mich. Totals may not add up exactly due to rounding.
Environmental benefits aside, the monetary savings of leaving the car at home can also be substantial. According to the American Public Transportation Association, an organization that advocates for the advancement of public transit, residents in some of the country's largest cities can save over $10,000 annually on parking and fuel costs by taking public transit instead of driving to work. The organization estimates that New Yorkers stand to save the most money—an average of $14,600 annually—by ditching the car and taking public transit.
Of course, there is no reliable data for which cities have the most drivers of hybrid or electric vehicles, which also help to reduce commuters' carbon footprints. But as these types of cars become more ubiquitous on America's roadways, the picture of what makes for earth-friendly transit is also sure to change rapidly.