San Francisco was first inhabitated in 3000 B.C by the Ohlone people. It was first visited by westenerners in 1769 in an expedition by the Spanish. A couple years later, it was taken over and a mission was established, Mission San Francisco de Asis.

In 1821, Mexico gained Independence from Spain and gained land previously owned by Spain. San Francisco was renamed Yerba Buena. By the 1840s, many Americans had come to Alta California and soon it became the California Republic. It wasn't long until California joined the Union, the US flag was raised in Yerba Buena's plaza on July 9, 1846. Soon after, the Gold Rush began and San Francisco went through a stage of rapid growth. The construction of the Transcontinental Railroad brought many laborers from China. San Francisco's Chinatown became the largest Chinese settlement outside of China.

In 1906, an earthquake with a Richter scale of 7.6 ruptured in San Francisco, causing massive damage to the city. The city rebuilt quickly and became a major arms production center for WWII. After the bombing of Pearl Harbor, many Japanese Americans were forced to move to internment camps far inland.

San Francisco gained a reputation of welcoming openly gay and lesbian people. The Castro District soon became a center of the gay rights movement. In 1989, San Francisco was hit with another large earthquake. A decade later the city was hit with a wave of entrepreneurs because of the rise of technology.