The state where I grew up – Wyoming – prides itself on wide open spaces, clean air and abundant wildlife. It’s the kind of place many people envision when they think of green living. But in reality, dense urban areas like New York City are usually more environmentally friendly overall. It’s not that city dwellers are necessarily more eco-aware or conscientious, but live in a setting with built-in efficiencies.

Wyoming has one of the largest carbon footprints per capita of any state in the U.S. It’s largely a function of people traveling hundreds of miles to the nearest city for shopping or for entertainment. Wyomingites will commonly travel 200 to 300 miles or more each way – often in a single day – to watch their beloved UW Cowboys play. Plus, most of the state’s electricity comes from coal-fired plants. But hardly anyone recognizes the huge emissions per person since there are relatively few of them and the pollutants are dispersed over wide areas, not in a concentrated space as in a city.

By comparison, residents of New York City (especially Manhattan) use about half as much gasoline per person as those living in Wyoming. The high density allows people to walk or use mass transit. Plus, the dwellings (primarily apartments in multi-story buildings) are more energy efficient to heat since they’re smaller and hot air from one unit rises to the next, rather than being lost out the roof like a single family home.

But how many people stop to consider that living in a gray city full of high rises is cleaner overall than a home next to a clear mountain lake or one in a small town? It’s common to think that constructing an ultra-modern home in a pristine natural setting full of trees is somehow greener because you’re next to nature and using the latest technologies, but the fact is it’s just taking the impacts of an urban area and spreading them to new locations. Such homes often require large amounts of new infrastructure – from roads to sewer to power – and long commutes, which can more than offset any efficiencies from solar panels and a tight envelope. Of course those things are important, but how green a home is needs to be considered as part of a larger set of impacts.

For example, a LEED Platinum home in the Mountain West last year received wide-spread attention in many national media for being a model of green technology. It has a cutting-edge passive solar design and a host of systems that make it net-zero energy. However, in singing its praises, no one asked the owner where he works. Turns out, he regularly commutes 120+ miles round trip. It likely would have been greener for him to build a more standard home in the town where he works -- or refurbish an existing home -- and reduce all the impacts from driving. But, since such green actions aren’t sexy, they usually get little attention.

For fascinating insights on why urban areas are the greenest places of all, check out David Owen’s book Green Metropolis. It shows how sometimes the best solution to a problem – in this case, living green – can be the opposite of what people expect.