The San Bernardino principal meridian was established in 1852, and governs all PLSS surveys in southern California, and some townships in western Arizona. The Initial Point—located at 34°07’13”N latitude, 116°55’48”W longitude—lies atop the summit of Mount San Bernardino in San Bernardino County, California, at over 10,000 feet of elevation. It is one of the most difficult initial points to reach in the United States due to the steep, rugged terrain. Survey townships were run both north and south of the San Bernardino base line, terminating at the Mount Diablo Meridian territory in the north, and terminating at the California-Mexico border in the south. Ranges were run east of the meridian to the Pacific Ocean, and west of the meridian to the Colorado River.
