From the plaque:
On March 16, 1774, Juan Bautista
de Anza, Indian fighter, explorer and colonizer, led through this pass (named by him San Carlos) the first white explorers to cross the mountains into California. The party traveled from
Tubac, Arizona to Monterey California. On December 27, 1775, on a
second expedition into California, Anza led through this
pass the party of Spaniards from Sonora who became the
founders of San Francisco.
Tablet placed by Historic Landmarks Committee, Native Sons of the Golden West. 1924.