America's Cleanest Commutes

When it comes to getting to and from the office, however, that's just not the case. In terms of commutes, some of the largest cities in the U.S. are the kindest to the environment. The San Francisco metro area, with its vaunted mass-transit system and relative dearth of solo drivers, tops our list of America's cleanest commutes. The country's three largest cities all rank in the top 10.

"I'm not surprised by that at all," says Sean Pool, an energy and environmental policy researcher for the Center for American Progress, a Washington, D.C. think tank. "Higher density makes public transit more effective. You get more bang for your buck."

Honolulu ranks second on our list thanks in part to its sterling 15.9% carpool rate; Washington, D.C., with its extensive subway system, ranks third. The Seattle and New York City metro areas round out the top five.

Behind the Numbers To determine our list, we used data released Monday by the Census Bureau as part of its annual American Community Survey. Last year, only 5.3% of America's 140 million laborers used mass transit to get to work. So in formulating our list, we considered all areas with at least 275,000 inhabitants and a mass transit rate better than the national average.

Only 15 metropolitan statistical areas--geographic entities defined by the U.S. Office of Management and Budget for use by federal agencies in collecting, tabulating and publishing federal statistics--met those criteria. Notable absentees included large metro areas such as Atlanta, where a mere 3.7% of workers commuted via mass transit; and Dallas, where only 1.7% of workers did.

We ranked the 15 qualifying metros in three categories: Percentage of workers commuting via mass transit, percentage of workers carpooling and percentage of workers driving alone (the first two measures being positive, the third negative). We assigned points to each metro area based on these categories to form our list.

A Tale of Two Cities Somewhat predictably, the Big Apple fared well in our ranking of clean commutes. But perhaps more surprising is that America's second-most populous city, Los Angeles--sprawling and heavily reliant on cars--takes the 10th spot on the list.

The City of Angels ranks well in terms of clean commutes due to its surprisingly strong performance in all three categories we considered. Though 72.8% of Los Angelinos drive alone to work, that's still better than the national average of 75.5%; the area's carpool rate of 11.5% is among the best in the nation thanks in part to regional initiatives aimed at reducing congestion and pollution. And although Los Angeles has a reputation for traffic and smog, 6.3% of its residents commute via mass transit--well above the national rate of 5.3%. That number gets a boost from the 18% of L.A. residents who live below the poverty line and have no choice but to rely on the city's extensive bus network.

New Yorkers, however, look to mass transit as their mode of choice. Nearly one-third of the 8.8 million workers in the New York metro area use the system, by far the best rate in the nation. In New York's densest pockets, some 80% of commuters use mass transit. The Big Apple and outlying suburbs are home to nearly half of the nation's 7.5 million mass-transit commuters.

New York's Metropolitan Transit Authority (MTA) is the largest in the nation, with 422 rail lines and bus routes and 2,057 track miles throughout the region. The MTA's Web site boasts that the transit system removes some 3 million drivers from the roads each day, absorbing more carbon emissions than 648,000 acres of forest could.

By the MTA's estimates, carbon dioxide emissions from public transit are about one-fifth the amount produced by single-occupancy vehicles on a per-rider basis, making New York very green on a per-capita basis.

William Blake would have been proud.