San Francisco, officially City and County of San Francisco is the cultural, commercial, and financial center of Northern California.
In 1846 the USA annexed the state of California. On 9 July 1846, USS Portsmouth sailed into San Francisco Bay and sailors and marines went ashore and raised the US flag. The little settlement of Yerba Buena was renamed San Francisco (after the bay) on 30 January 1847. At that time San Francisco only had a population of about 800. In 1848 news of the discovery of gold in the area reached New York. As a result people went to San Francisco by the thousands, and the population boomed. In 1849 the population of San Francisco reached 25,000.