Home rule cities are the most numerous in Michigan. Upon the enactment of the Home Rule Cities Act in 1909, all new cities were required to incorporate under this streamlined process, which allowed for a framework for incorporation and for a city to enact and amend its own charter without an act of the state legislature. To incorporate as a home rule city the area seeking incorporation must have a population of at least 2,000 and 500 people per square mile, though a 1931 amendment allowed existing villages within that population range to incorporate as cities without the population density requirement.