Mt. Diablo's name grew from a linguistic accident rooted in early Spanish encounters in the area. On an 1824 map, "M. del Diablo" referred to a Christian Indian village rather than the peak itself. The association with "diablo" can be traced to 1804 or 1805, when a Spanish military expedition searching for runaway mission Indians surrounded a village of Chupcan people at a willow thicket several miles northeast of here, near present-day Buchanan Field, only to find by morning that all the Indians had escaped; angered and confused, the Spanish called the place "Monte del Diablo," or Thicket of the Devil. Later English-speaking newcomers mistakenly transferred that name to the prominent East Bay peak, giving California its Devil Mountain. General Mariano Vallejo later offered a different version, placing the episode at the foot of Mt. Diablo and saying the Spanish were routed by an "unknown personage" or "evil spirit," while in 1914 his son Platon recast Mariano Vallejo as the hero who lassoed this agent of the devil. Mt. Diablo's unobstructed summit also became an important surveying reference point in the Far West: in 1851, Col. Leander Ransome established the Mt. Diablo initial point, from which survey lines extended north, south, east, and west to form a grid covering most of northern California and all of Nevada. The mountain also became a state park when a bill supported chiefly by Senator W. Starkey was signed into law on August 2, 1921, and in 1931 it was re-dedicated as a unit of the new State Division of Beaches and Parks. Between 1933 and 1942, Civilian Conservation Corps workers developed the young park by building roads and trails, ranger residences, and many camp and picnic facilities, and the stone summit building became their crowning achievement there.