Conventional wisdom seems to be that sprawl is bad for the planet and density is good. Does that automatically mean living in a city is better for the environment than living in a suburban or rural area? Not necessarily. How environmentally sound your lifestyle is depends less on where you live than how you live.

'Urbs

Manhattan, in many ways, is green. Most people use mass transit or walk, rather than drive. Most also live in apartments, which can be heated and cooled more efficiently than houses. Virtually no one has lawns, so there's little need for fertilizers and pesticides. "By the most significant measures, New York is the greenest community in the United States, and one of the greenest cities in the world," David Owen wrote in the New Yorker, in a story extolling the enviro virtues of living in New York City, specifically in Manhattan. "The true challenge," the article said, "is how to make other settled places more like Manhattan." Because what's true about Manhattan is not necessarily true about urban areas in general.

In Los Angeles, for instance, most people live in houses, some of them massive houses with huge lawns and swimming pools, and nearly all Angelenos drive. A lot. In Chicago, meanwhile, many apartments are in smaller buildings rather than big high-rises, so they aren't necessarily more energy efficient than single-family homes. Older cities, such as Boston or even San Francisco, are far denser and less car-reliant than newer cities like Phoenix, which are nearly indistinguishable from exurbs - making it tough to generalize about urban areas.

Still, some overarching observations are possible: urban areas tend to have higher concentrations of people per square mile, meaning they require less land per person. They also tend to have lower numbers of people driving, and therefore burn up less fossil fuel per capita.

'Burbs

Meanwhile, America's suburbs and exurbs are largely car cultures - with the exurbs being the worst offenders as the least likely to have public transportation options for commuting. There's little likelihood, outside of urban areas, that there's a supermarket or restaurant within walking distance, meaning you have to drive just about every time you leave your house. More land is disturbed for development, meaning less wilderness, less wildlife habitat, fewer intact ecosystems.

But living outside of urban centers can have its environmental payoffs. For starters, you can compost. Few cities have composting programs, so perfectly good organic waste ends up trapped forever in the landfill. (And then those same people who threw away their vegetable scraps have to go to the store to buy compost that's been trucked in from someplace else.) You're less likely to find scores of buildings with the lights left on all night, as is the practice in just about every big office building in every city. More food is likely to be locally grown.

The Upshot

So which is better for the environment, city or ‘burbs? There's no simple answer. You could live in Manhattan and ride the subway everywhere, but run your air conditioning six months of the year, eat takeout lunch from the deli each day - meaning Styrofoam containers, plastic utensils, paper cups, plastic bags - and upgrade your cell phone, laptop, and other electronics annually without recycling the old ones. Conversely, you could live in the suburbs but telecommute from your solar-powered home, or drive to your nearby office in your biodiesel-powered Jetta TDI, and on weekends ride your bike to the local farmers' market.

Photo credit: The Lancaster County Planning Commission