The history of San Francisco as a municipality is unique.

Two former Mexican pueblos, Yerba Buena and San Francisco, had been permitted to lapse and a Mexican Justice of the Peace exercised sole authority up to July 8, 1846, over the “Jurisdiction of San Francisco” which contained within its limits what remained of these two villages.

On July 8th, 1846, the American flag was hoisted on the plaza of Yerba Buena, and the surrounding territory was declared American soil. Military government prevailed until January 30th, 1847, when a provisional government was organized with an Alcalde as Chief Magistrate. The machinery provided by the Mexican colonization laws for the creation and government of pueblos was utilized and San Francisco as a municipality came into being by Ordinance of the Alcalde. Subsequently attempts were made before the treaty of Queretaro to organize a City along American lines, but were by military order stopped. Pueblo government continued until the adoption of a city charter under the Constitution of California.

An Act of the first Legislature of the State of California, passed February 18, 1850, divided the State into counties, fixing the boundaries of San Francisco County.

The City of San Francisco was created by Act of April 15, 1850, (Statutes 1850, page 223) which was an act to incorporate the City. This Act provided for a complete organization of the City and a full set of offices independent of the county offices of the County of San Francisco. Thus there were two sets of officers, one for the City and one for the County.