The Metropolitan Water District of Southern California is a regional wholesaler and the largest supplier of treated water in the United States. The name is usually shortened to "Met," "Metropolitan," or "MWD." It is a cooperative of fourteen cities, eleven municipal water districts, and one county water authority, that provides water to 19 million people in a 5,200-square-mile (13,000 km²) service area. It was created by an act of the California State Legislature in 1928, primarily to build and operate the Colorado River Aqueduct. Metropolitan became the first contractor to the State Water Project in 1960.