Farrell replaces Board President London Breed, who stepped in when former Mayor Ed Lee passed away in December 2017.
Farrell resigned his seat on the Board of Supervisors when he was sworn in as Mayor on January 23, 2018. He will serve until a special election is held for the position of Mayor on June 5, 2018.
Farrell is not a candidate in that race, but London Breed is running for Mayor.