<P> The mayor appoints the Commissioner of the Chicago Fire Department and Superintendent of the Chicago Police Department . He or she also appoints the heads of city departments, the largest of which are the Water Management Department (formed by the consolidation of the former Water Department and Sewer Department under Richard M. Daley) and the Streets & Sanitation Department . He or she also appoints members to the boards of several special - purpose governmental bodies including the Chicago Park District, Chicago Public Library, Chicago Housing Authority, Chicago Transit Authority, and the Metropolitan Pier and Exposition Authority . Under Richard M. Daley, the Illinois legislature granted the mayor power to appoint the governing board and chief executive officer of the Chicago Public Schools and subordinated the district to the mayor; the district had long been an independent unit of government . </P> <P> The Chicago City Clerk and City Treasurer are elected separately, as are the 50 aldermen who form the City Council . The mayor is empowered, however, to fill vacancies in any of these 52 elected offices by appointment . In turn, the City Council elects one of its own to fill a mayoral vacancy . </P> <P> The Mayor of Chicago is elected by popular vote every four years, on the last Tuesday in February . A run - off election, in the event that no candidate garners more than fifty percent of the vote, is held on the first Tuesday in April . The election is held on a non-partisan basis . Chicago is the largest city in the United States not to limit the term of service for its mayor . </P> <P> In accordance with Illinois law, the City Council elects a Vice-Mayor (currently Ald . Brendan Reilly (42nd), since May 2015) who serves as Interim Mayor in the event of a vacancy in the office of the Mayor or the inability of the Mayor to serve due to illness or injury until the City Council elects one of its members acting Mayor or until the mayoral term expires . However, if a vacancy occurs in the office of Mayor with more than 28 months remaining in the mayoral term and at least 130 days before the next general municipal election, then a special election must be held to choose a new Mayor to serve out the remainder of the term at that general municipal election; if a vacancy occurs with less than 28 months remaining in the mayoral term or less than 130 days before the next general municipal election, then the acting Mayor serves as Mayor until the mayoral term expires . </P>

When does chicago vote for a new mayor
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