The majority of public lands in the United States are held in trust for the American people by the federal government and managed by the Bureau of Land Management (BLM) or the U.S. Fish and Wildlife Service under the Secretary of Interior or the U.S. Forest Service under the U.S. Department of Agriculture. National Parks and Monuments are also public lands managed by the National Park Service, which is also part of the Interior Department. Other federal agencies that manage public lands include the National Oceanic and Atmospheric Administration, the Bureau of Reclamation, and the Army Corps of Engineers.

Wilderness is a special designation for public lands which have been completely undeveloped. Wilderness areas can be managed by any of the above Federal agencies, and some parks and refuges are almost entirely designated wilderness. A wilderness study area is a tract of land that has wilderness characteristics, and is managed as wilderness, but has not received a wilderness designation from Congress.

Recreation on U.S. public lands

Most state- and federally managed public lands are open for recreational use. Recreation opportunities depend on the managing agency, and run the gamut from the free-for-all, undeveloped wide open spaces of BLM lands to the highly developed and controlled national and state parks. Wildlife refuges and state wildlife management areas, managed primarily to improve habitat, are generally open to wildlife watching, hiking, and hunting, except for closures to protect mating and nesting, or to reduce stress on wintering animals. National forests generally have a mix of maintained trails and roads, wilderness and undeveloped portions, and developed picnic and camping areas.

(Wikipedia)