Georgia has 500 cities in 159 counties with 13 congressional districts. 149 of the 159 in the state are governed by a committee of around three to eleven commissioners while the other 10 are overseen by a single commissioner. Most of the 536 cities are governed by a mayor-council system. Georgia has almost eight million acres (32,000 km2) of prime farmland while over 60% of the land is made up of pine forests. Georgia has 70,150 miles (112,900 km) of streams and rivers, 425,000 acres (1,720 km2) of lakes, and approximately 4,500,000 acres (18,000 km2) of freshwater wetlands. Manganese, iron, copper, among and other minerals make up the natural resources of the state.