America's Greenest Cities

A solid majority, 71% of Americans, believe the country “should do whatever it takes to protect the environment,” according to a 2014 poll by the Pew Research Center.

This strong public interest in our environment extends to urban living, prompting NerdWallet’s curiosity: Even though we all know that the city we live in influences our transportation and energy choices, how do environmental impacts differ across the U.S.?

We explored the data for the nation’s 150 largest cities to shed light on the best places for those seeking a green lifestyle and a healthy environment.

NerdWallet’s analysis

Environmental quality. To uncover the impact of pollution on residents’ health, we looked at each city’s 2014 median of the U.S. Environmental Protection Agency’s daily Air Quality Index — a measure of sulfur dioxide, carbon monoxide, nitrogen dioxide and ozone levels that guide the assessment of acute health effects. The higher the index number, the more polluted an area. In most cases, air quality in U.S. cities has a median index score under 100, which falls into the EPA’s “moderate” range.

Transportation. To understand how cities might influence lifestyle choices, we looked at data from the U.S. Census Bureau’s American Community Survey on commuting methods to find out how many workers are walking, biking, carpooling and taking public transit.

Energy sources. To gain insight into the fuels people are using in each city, we looked at data from the American Community Survey on heating in homes. We were specifically interested in the number of homes using coal and wood because these fuels are particularly harmful. We also examined the use of solar energy because of its sustainability.

Housing density. Urban sprawl increases transportation needs and resource use, so we looked at data from the American Community Survey on the percentage of residential buildings with 10 or more residences in each city.

What we learned

Bigger is better. We might associate larger cities with polluting industries, but bigger cities tend to be denser, which reduces urban sprawl and energy needs for transportation per capita.

Air quality is fairly uniform. Many of the cities we examined fall within a narrow range of the EPA’s Air Quality Index, sitting between the classification of “good,” an index number under 51, and “moderate,” a number under 101. Of course, there are notable outliers, like Riverside, California, where the air quality about 30 days in 2014 reached “unhealthy” levels over 150.

Traditional fuels remain. Although solar power is part of mainstream energy conversations, the data suggest adoption is lagging. Nationwide, out of 116 million homes, only 72,707 houses use solar heating, up from 2005 when the number was 36,682, while the use of traditional heating methods — including coal and wood — have remained stable.

America’s greenest cities

1. Honolulu, Hawaii

2. Washington, D.C.

3. Arlington, Virginia

4. San Francisco, California

5. Miami, Florida

6. New York City, New York

7. Boston, Massachusetts

8. Orlando, Florida

9. Seattle, Washington

10. Jersey City, New Jersey

To find out why these cities made the Top 10 List and to check out the Top 25 List - Visit NerdWallet.

Green city image via Shutterstock.