The post of Mayor of the City of New Orleans (French: Maire de La Nouvelle-Orléans) has been held by the following individuals since New Orleans came under American administration following the Louisiana Purchase — the acquisition by the U.S. of 828,800 square miles (2,147,000 km2) of the French province La Louisiane in 1803. In mayoral elections since 1930, New Orleans has used a two-round system with a preliminary round and a runoff if no candidate reached a majority in the first round.