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.