More history

After I found out about the CandO canal, I found this information:

The Anacostia Substation, opened in 1970, had 36 officers under Lt. Thomas J. McDonnell responsible for Anacostia Park, the Suitland Parkway, Fort Washington Park, and other parklands in eastern Washington and nearby Maryland. Although the parks they served were old Park Police responsibilities, the current Rock Creek Park and George Washington Memorial Parkway substations opened in 1971. Lt. Richard E. Magee commanded the 29 officers assigned to the Rock Creek Park Substation, with jurisdiction over numerous park areas in Northeast and Northwest Washington in addition to Rock Creek Park. Lt. W. Franklin Stevens had 39 officers under him at the George Washington Memorial Parkway Substation, located at Glen Echo Park, Maryland. They covered the parkway on both sides of the river, Wolf Trap Farm Park, Arlington National Cemetery, and the Cheasapeake and Ohio Canal National Historical Park as far as Seneca, Maryland.