The rest of the world is building subways like crazy. The U.S. has pretty much given up
(www.fastcompany.com)
America is stretched out, but that mostly referred to Alaska and everything west of the Mississippi and a narrow line of the Pacific ocean. Stick to east of the Mississippi or within 50 miles of the Pacific ocean and you find Americans are dense enough for good transit. However nobody builds good transit, and we are not dense enough to put up with bad transit.