SMITHTOWN, NY – Community leaders in Smithtown, N.Y., have decided that by January, all city trash-collection trucks will run on natural gas instead of diesel fuel. Smithtown is the first East Coast city to impose such a mandate. Trash trucks today average only 2.8 miles per gallon and burn about 8,600 gallons of diesel fuel each year. There are more than 136,000 refuse trucks on American streets, according to the New York Times. From 2002 to 2005, the number of communities in the U.S. using natural gas trucks doubled — from 26 to 57. The number of trucks expanded from 750 to nearly 1,500.