William Leidesdorff - in San Francisco

In San Francisco

On arriving at Yerba Buena, Leidesdorff, Jr. began to re-build his businesses. The village cove then only had thirty European-Mexican families, so it did not take long for the ambitious man to make an impact. He launched the first steamboat to operate on San Francisco Bay and the Sacramento River; it was 37 feet (11 m) long and purchased in Alaska. He built the City Hotel, the first hotel in San Francisco, and the first commercial shipping warehouse, the latter on what became Leidesdorff Street off the Embarcadero.

In 1844 Leidesdorff obtained a vast land grant through favor from the Mexican government for 35,521 acres (143.75 km2) on the south bank of the American River, near today's Californian City of Sacramento. He named the property Rancho Rio de los Americanos. During this period, Mexico encouraged leading Americans to settle in its territory by granting large land grants; in exchange the government required Americans to convert to Catholicism, the state religion; learn to speak Spanish; and accept Mexican citizenship. He went on to establish extensive commercial relations throughout Hawaii, Alaska and Mexican California.

During the eight years of his residence, Leidesdorff served as one of six aldermen or town councilors of the Ayuntamiento. After the United States took over California following the Mexican-American War, he was one of three members on the first San Francisco school board, which organized the first public school in the city; later he was elected City Treasurer. His house was one of the largest, and he donated land for the first public school.

In 1845, during the President James Polk administration, Leidesdorff accepted the request from US Consul Thomas O. Larkin to serve as the US Vice Consul to Mexico at the Port of San Francisco, a measure of his political standing in region. Larkin was the first and last U.S. Consul appointed to serve in California. Before the American flag was raised over San Francisco (July 1846), Leidesdorff had the U.S. Declaration of Independence read for the first time in California on the veranda at his home in celebration of Independence Day.

Leidesdorff, Jr. achieved a high reputation for integrity and enterprise; he is said to have been "liberal, hospitable, cordial, confiding even to a fault." Leidesdorff became one of the wealthiest man in California. The value of his property near Sacramento began to rise dramatically just before his death, when gold was discovered along the American River just above his Leidesdorff Ranch, in the Gold Mining District of California.

In March 1848, the California Star reported the total non-Native population of San Francisco as only 812: 575 males, 177 females and 60 children. In May 1848, the vast majority of men departed for the American River gold fields in hopes of striking it rich. Other towns were nearly emptied in the frenzy of the Gold Rush.