Under the constitutions of 1935, 1973, and 1987, the country has been divided into provinces, municipalities, and chartered cities, each enjoying a certain degree of local autonomy. Each of the 73 provinces and subprovinces elects a governor, a vice-governor, and two provincial board members for terms of six years. There are 61 chartered cities headed by a mayor and a vice-mayor. Chartered cities stand on their own, are not part of a province, do not elect provincial officials, and are not subject to provincial taxation, but have the power to levy their own taxes. Municipalities, of which each province is composed, are public corporations governed by municipal law. There are approximately 1,500 municipalities, and within each municipality are communities ( barangays ), each with a citizens' assembly. There are about 42,000 barangays . The 1987 constitution provides for special forms of government in the autonomous regions created in the Cordilleras in Luzon and the Muslim areas of Mindanao. Any region can become autonomous by a referendum. The Local Government Code of 1991 provided for a more responsive and accountable local-government structure. Local governments are to be given more powers, authority, responsibilities and resources through a system of decentralization.