The Piscataway Indian Tribe made this section of Southern Maryland its winter camping ground because of the mild climate and abundance of game. Legend says there is an Indian Burial ground in Cedarville State Forest, but to date it has not been found. The headwaters of the Zekiah Swamp are located in Cedarville. The swamp extends Southward through Charles County for 20 miles, emptying into the Wicomico River. The Swamp is one mile wide, and serves as a haven for wildlife. The surrounding land is mostly agricultural fields. In colonial times and there after efforts were made to drain the swamp for cultivation. Drainage ditches are still evident. To this day, the swamp remains wooded bottom land.
In 1930, the Maryland Department of Natural Resources, Forest, Park and Wildlife Service purchased 2,631 acres of land for a forest demonstration area. Later 879 more acres were added to bring the total to 3,510 acres. Cedarville was the postal address for the area, hence the name given to the State Forest. In 1933, the Civilian Conservation Corps, under the direction of President Franklin D. Roosevelt, developed roads and trails for fire protection and future access for the development of the area.