Top 10 green U.S. cities

The Windy City has embraced land sustainability far longer than you may think. In 1909, pioneering city planner Daniel Hudson Burnham created a long-range plan for the lakefront that balanced urban growth, and created a permanent greenbelt around the metropolitan area. This greening of the city continues through the Chicago Green Roof Program. More than 2.5 million square feet of city roofs support plant life — including Willis Tower (formerly called Sears Tower) and the city hall building. Also, about 500,000 new trees have been planted.