National Wilderness Preservation System

The National Wilderness Preservation System (NWPS) of the United States protects federally managed wilderness areas designated for preservation in their natural condition. Activity on formally designated wilderness areas is coordinated by the National Wilderness Preservation System. Wilderness areas are managed by four federal land management agencies: the National Park Service, the U.S. Forest Service, the U.S. Fish and Wildlife Service, and the Bureau of Land Management.

The term wilderness is defined as "an area where the earth and community of life are untrammeled by man, where man himself is a visitor who does not remain" and "an area of undeveloped Federal land retaining its primeval character and influence, without permanent improvements or human habitation, which is protected and managed so as to preserve its natural conditions".

As of 2023^[update], 806 wilderness areas have been designated, totaling 111,889,002 acres (45,279,873 ha; 452,798.73 km²; 174,826.566 sq mi), which comprise about 4.5% of the land area of the United States.

During the 1950s and 1960s, as the American transportation system was on the rise, concern for clean air and water quality began to grow. A conservation movement began to take place with the intent of establishing designated wilderness areas. Howard Zahniser created the first draft of the Wilderness Act in 1956. It took nine years and 65 rewrites before the Wilderness Act was finally passed in 1964. The Wilderness Act of 1964 (Public Law 88-577), which established the NWPS, was signed into law by President Lyndon B. Johnson on September 3, 1964. The Wilderness Act mandated that the National Park Service, U.S. Forest Service, and U.S. Fish and Wildlife Service review all federal lands under their jurisdiction for wilderness areas to include in the NWPS. The first national forest wilderness areas were established by the Wilderness Act itself. The Great Swamp in New Jersey became the first National Wildlife Refuge with formally designated wilderness in 1968. Wilderness areas in national parks followed, beginning with the designation of wilderness in part of Craters of the Moon National Monument in Idaho in 1970.

A dramatic spike in acreage added to the wilderness system in 1980 was due in large part to the Alaska National Interest Lands Conservation Act, signed into law by President Jimmy Carter on December 2, 1980. A smaller spike in 1984 came with the passage of many bills establishing national forest wilderness areas identified by the Forest Service's Roadless Area Review and Evaluation (RARE) process. The Bureau of Land Management was not required to review its lands for inclusion in the NWPS until after October 21, 1976, when the Federal Land Policy and Management Act of 1976 was signed into law; designation of wilderness areas on BLM lands began in 1978. Over 200 wilderness areas have been created within Bureau of Land Management administered lands since then, consisting of approximately 8.71 million acres (3,520,000 ha) in September 2015.

As of August 2008, 704 separate wilderness areas, encompassing 107,514,938 acres (43,509,752 ha), had become part of the National Wilderness Preservation System. On March 30, 2009, President Barack Obama signed into law the Omnibus Public Land Management Act of 2009. The legislation designated an additional 2 million acres (810,000 ha) in nine states as wilderness, representing the largest expansion of wilderness lands since 1994. The John D. Dingell Jr. Conservation, Management, and Recreation Act of 2019 added another 1.3 million acres (530,000 ha) in 43 new and expanded wilderness areas.

On federal lands in the United States, Congress may designate an area as wilderness under the provisions of the Wilderness Act of 1964. Multiple agencies, including the Bureau of Land Management, the National Park Service, the Fish and Wildlife Service, and the U.S. Forest Service, are responsible for the submission of new areas that fit the criteria to become wilderness to Congress. Congress then reviews these cases on a state by state basis and determines which areas and how much land in each area will become part of the WPS. There have been multiple occasions in which Congress designated more federal land than had been recommended by the nominating agency. Where as the Wilderness Act stipulated that a wilderness area must be "administered for the use and enjoyment of the American people in such a manner as will leave them unimpaired for future use and enjoyment as wilderness", the Eastern Wilderness Areas Act of 1975, which added 16 national forest areas to the NWPS, allowed for the inclusion of areas that had been severely modified by human interference.

The Wilderness Act provides criteria for lands being considered for wilderness designation. Though there are some exceptions, the following conditions must be present for an area to be included in the NWPS: (1) the land is under federal ownership and management, (2) the area consists of at least five thousand acres of land, (3) human influence is "substantially unnoticeable," (4) there are opportunities for solitude and recreation, and (5) the area possesses "ecological, geological, or other features of scientific, educational, scenic, or historical value."