In 1848 gold was discovered in the interior of California, near Sacramento, and the ensuing gold rush rapidly transformed San Francisco into a booming community. San Francisco was incorporated as a city in 1850.
The city developed as a port and supply point and became an early governmental and cultural centre. It was noted for its cosmopolitan population and for the lawlessness of some sections, particularly the so-called Barbary Coast area. In 1869 the transcontinental railway reached the Bay Area, and by 1900 San Francisco had more than 340,000 inhabitants. On April 18, 1906, a major earthquake shook the city and caused a fire that raged for three days, destroying almost all of San Francisco's city centre and much of the residential area. Despite this, the city was quickly rebuilt. The city was again badly damaged by an earthquake in 1989, but has since recovered. In 1934 a strike by 12,000 San Francisco longshoremen spread to a dozen Pacific Coast cities and resulted in a three-day general strike that paralysed the city.
During World War II San Francisco was a major shipbuilding centre and in 1945, at the end of the war, the city was the site of an international conference that drafted the United Nations Charter. In the 1960s and 1970s many large modern buildings were constructed in the city, and a number of residential areas were revitalized. In the late 1950s the literary development of the Beat Generation was located in San Francisco's North Beach area and the city has long been famous for its alternative cultures. The city's significant gay population has made it a major centre of gay civil rights activism since the 1970s. Population (1980) 678,974; (1990) 723,959.