Reply #3: This has been well known in the environmental field for a long time

[HamdenRice]

Just consider the difference between heating a stand alone home in the distant suburbs to heating a small apartment surrounded by other apartments. Also, every person living in an apartment in New York is a person not destroying a 1/4 acre or more of northeast woodland. All cities are greener than suburbs, exurbs and rural areas.

What makes New York especially green, though is the subway system and the culture of walking and taking mass transit. New Yorkers think nothing of walking a mile or more in the city, and when people visit us from out of town they literally can't take the physical exertion that we don't even think about.

That's why so many New Yorkers are thin.