The Colorado River is the principal river of the Southwestern United States and northwest Mexico. The 1,450-mile (2,330 km) river drains an expansive, arid watershed that encompasses parts of seven U.S. and two Mexican states. Rising in the central Rocky Mountains in the U.S., the river flows generally southwest across the Colorado Plateau and through the Grand Canyon before reaching Lake Mead on the Arizona–Nevada line, where it turns south toward the international border. After entering Mexico, the Colorado approaches the large Colorado River Delta where it naturally emptied into the Gulf of California between Baja California and Sonora, though it no longer reaches its delta or the sea.