The Union Labor Party was a San Francisco, California working class political party of the first decade of the 20th century. The organization, which endorsed the doctrine of nativism, rose to prominence in both the labor movement and urban politics in the years after 1901, electing its nominee as Mayor of San Francisco in 1901, 1903, 1905, and 1909.

The mayor of the City and County of San Francisco is the head of the executive branch of the San Francisco city and county government. The officeholder 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 have been governed together by a combined set of governing bodies since 1856.