Marion County, Indiana
The low rolling hills of Marion County have been cleared of trees, and the area is completely devoted to municipal development or to agriculture, except for wooded drainages. The highest point (920 feet/279 meters ASL) is a small ridge at the county’s northwest corner.
According to the 2010 census, the county has an area of 403.01 square miles (1,043.8 km2), of which 396.30 square miles (1,026.4 km2) (or 98.34%) is land and 6.71 square miles (17.4 km2) (or 1.66%) is water.
The White River flows southwestward through the central part of the county; it is joined by Eagle Creek and Fall Creek, both of which have dams in the county forming Eagle Creek Reservoir and Geist Reservoir, respectively.
Marion County was created on April 1, 1822, from part of the “New Purchase” lands that had been obtained from its inhabitants, the Lenape, by the Treaty of St. Mary’s. It is named for Francis Marion, a brigadier general from South Carolina in the American Revolutionary War.
The state capital was moved to Indianapolis in Marion County from Corydon on January 10, 1825. This began a period of rapid growth in population.
Marion County is consolidated with Indianapolis through an arrangement known as Unigov.