The Mission district refers to an area of San Francisco surrounding the original settlement's 18th century church, dedicated to St. Francis of Assisi.
In the 20th century, Mercy Hospital was located in the Mission district (Star Trek IV: The Voyage Home).
Originally a bastion in the city for persons coming from the nation-state of Mexico, by the late 24th century, the Mission district was home to many Starfleet officers.
One of the Trans-Francisco public transit system's subway lines runs through the Mission district (VOY: "Non Sequitur").