Miscellaneous Data for the United States: Highest point:Mount McKinley, Alaska20,320 ft. (6,198 m) Lowest point:Death Valley, Calif.282 ft. (86 m) below sea level Approximate mean elevation2,500 ft. (763 m) Points farthest apart(50 states): Log Point, Elliot Key, Fla., and Kure Island, Hawaii5,859 mi. (9,429 km) Geographic center(50 states): in Butte County, S.D. (west of Castle Rock)44°58'N lat.103°46'W long. Geographic center(48 conterminous states): in Smith County, Kan. (near Lebanon)39°50'N lat. 98°35'W long. Boundaries: Between Alaska and Canada1,538 mi. (2,475 km) Between the 48 conterminous states and Canada (incl. the Great Lakes)3,987 mi. (6,416 km) Between the United States and Mexico1,933 mi. (3,111 km) Source:U.S. Geological Survey.