Halifax, formally known as the Halifax Regional Municipality, was created in April 1996 with the amalgamation of four smaller municipalities. The Halifax Regional Council was formed at the time of the HRM's incorporation and consisted of twenty-three councillors and one mayor. It was reduced in size to sixteen councillors and the mayor in 2012. The council meets at Halifax City Hall. Elections are held every four years on leap years. By-elections for council seats have been held in 1998, 1999, 2003, 2006 and 2007 after some regional councillors were elected to the provincial legislature.