When Payne Stewart (the golfer) was part of a small plane disaster, the two F-16 chase planes that were dispatched to make sure that all went well were "destruction-enabled", with the option to shoot the plane down should it endanger any population center. (They didn't need to - the aircraft finally went down out there in the middle of nowhere.)
The probability that any purely ballistic object (one that follows a consistent trajectory) would strike a human being, much less a city-sized area when aimed at a "target" the size of the United States is very, very low. The same holds true for the world as a whole - throughout recorded history, there has only been one documented instance of anyone hit by a meteorite.
Look at any of those satellite images taken at night that show the lights - there's a very small amount of very bright areas, some speckles here and there elsewhere, and a whole lot of black in between. In overall terms, the United States is overwhelmingly rural, perhaps as much as 98% of farmland, ranch land or empty terrain.
Of course, sitting in metropolitan Houston (as I am right now) or in the East Coast conurbation, it's hard to see things from that perspective...
