High Quality Content by WIKIPEDIA articles! he Mayor of the City and County of San Francisco is the head of the executive branch of San Francisco's city and county government. The mayor has the duty to enforce city laws, and the power to either approve or veto bills passed by the San Francisco Board of Supervisors, the legislative branch. The mayor serves a four-year term and is limited to two successive terms. Because of San Francisco's status as a consolidated city-county, the mayor also serves as the head of government of the county; both entities has been governed together by a combined set of governing bodies since 1856.There have been 41 individuals sworn into office. John W. Geary, elected in 1850, was the first mayor of the city. Charles James Brenham, who served as mayor during the 1850s, is the only person who has served two non- consecutive terms. The current mayor is Gavin Newsom; he was first elected on December 9, 2003 in a runoff election, replacing his predecessorWillie Brown. He was re-elected to a second term on November 6, 2007, and his term is scheduled to expire on January 8, 2012.