Washington, DC, has one car-free street: the stretch of Pennsylvania Avenue NW between 15th and 17th Streets. The odd thing is that the street was closed after

Washington, DC, has one car-free street: the stretch of Pennsylvania Avenue NW between 15th and 17th Streets. The odd thing is that the street was closed after a man crashed an airplane on the White House lawn. (I except the case of blizzards--with a couple of feet of snow, you can ski or play tackle football in the middle of a main street.)