This list of National Park System areas in Maryland includes the lands, trails, or park networks maintained by the National Park Service of the United States within the U.S. State of Maryland. The National Park Service controls 24 units in the state of Maryland. They range from sites of historical interest to sites of ecological interest to portions of the parkway system around Washington, DC. Many of the sites currently under the control of the National Park Service in Maryland were previously under the control of other agencies in the federal government, such as Antietam National Battlefield, which was originally managed by the Department of War.[1] There are eight units administered by the National Park System as part of the National Capital Parks. The most recent unit created in Maryland is the Captain John Smith Chesapeake National Historic Trail, which was authorized by Congress in 2006.