A national recreation area (NRA) is a protected area in the United States established by an Act of Congress to preserve enhanced recreational opportunities in places with significant natural and scenic resources. There are 40 NRAs, which emphasize a variety of activities for visitors, including hiking, camping, boating, fishing, swimming, biking, horseback riding, and wildlife viewing, in areas that include multiple-use management for both conservation and limited utilization of natural resources. The first, Lake Mead NRA (pictured), was created by a 1936 agreement between the United States Bureau of Reclamation, which had built Hoover Dam, and the National Park Service, which had experience in managing visitors in the outdoors. NRAs are managed by the NPS, the United States Forest Service (USFS), and the Bureau of Land Management. NRAs are located in 26 states; California and Washington have the most, each with four. NRAs of the USFS have a total area of 3,261,818 acres (13,200 km2), and those of the NPS total 3,714,735 acres (15,033 km2). (Full list...)