Mount Diablo meridian
The Mount Diablo Meridian, established in 1851, is a principal meridian extending north and south from its initial point atop Mount Diablo in California at W 121° 54.845. Established under the U.S. Public Land Survey System, it is used to describe lands in most of northern California and all of Nevada. Mount Diablo also marks the baseline at latitude 37°52′54″N.