San Francisco is a large city located in California on the west coast of North America, USA. Founded in the 1840s, it is known for its ethnically diverse population, and as a center of arts and culture. Several of Starfleet's key institutions are based here, including Starfleet Academy, Starfleet Command, Starfleet Operations, and Starfleet Headquarters.
The location of San Francisco as Starfleet Headquarters was an extremely controversial one which created a conflict between those that thought HQ should be located on the surface of a planet and those that believed that HQ should be located in deep space at a space station. The Romulan attack on the Mitlas station followed by the defense of Tarkon III decisively shifted the debate in favor of locating HQ on a planet as it illustrated the extreme vulnerability of space stations to raids.
The current city boundaries of San Francisco extend far beyond the municipal boundaries of the "Old City" in the 21st century and includes Oakland, Santa Clara, San Jose, and north to Petalum and Napa.
The Underground City
The conversion of San Francisco to become headquarters of Starfleet has created what is known as the underground city. For defensive reasons, much of the actual operations work for Starfleet HQ takes place in deep underground centers that are hardened against nuclear attack as well as transporter bombs. There are multiple redundant command centers under San Francisco along with the ability to transfer rapidly shift command and control functions in case of a decapitation strike. See the Hydra Criterion
San Francisco is governed as a Special Federation District which is directly under the governance of the jurisdiction of the Federation and hence outside that of the United Nations. The city legislature consists of a 25 person Board of Supervisors elected on a district by district basis, and a Mayor that is elected by popular vote. Terran residents may vote in elections to the United Nations General Assembly but not to the United States Congress or state of California elections.
Because Starfleet cadets and diplomats can vote in city elections but not UN elections, the San Francisco Board of Supervisors has become an unofficial forum for interaction between Starfleet personnel and local residents. Districts 15 and 18 are especially known for their heavy turnout of Starfleet personnel and the council member for District 15 has been often termed the unofficial Mayor of Starfleet.
Owing to its special status as a Federation District, the taxes within San Francisco are considerably lower than that of the surrounding regions giving it a unintentional status as a free port.
The boundaries of the San Francisco Federation District has been a topic of persistent controversy. There is strong desire by Federation HQ to expand the boundaries of the District, but efforts to do so have been complicated both by resistance from Terra First supporters and by local officials that are upset at the possible loss of tax revenue.