Federal lands

Federal lands are lands in the United States owned by the federal government. Pursuant to the Property Clause of the United States Constitution (, section 3, clause 2), the Congress has the power to retain, buy, sell, and regulate federal lands, such as by limiting cattle grazing on them. These powers have been recognized in a long line of U.S. Supreme Court decisions. 
The federal government owns about 640 million acres of land in the United States, about 28% of the total land area of 2.27 billion acres. The majority of federal lands (610.1 million acres in 2015) are administered by the Bureau of Land Management (BLM), U.S. Fish and Wildlife Service (FWS), National Park Service (NPS), or U.S. Forest Service (FS). BLM, FWS, and NPS are part of the U.S. Department of the Interior, while the Forest Service is part of the U.S. Department of Agriculture. An additional 11.4 million acres of land (about 2% of all federal land) is owned by the U.S. Department of Defense (DOD). The majority of federal lands are located in Alaska and the Western states.
Legal background.
The United States Supreme Court has upheld the broad powers of the federal government to deal with federal lands, for example having unanimously held in "Kleppe v. New Mexico" that "the complete power that Congress has over federal lands under this clause necessarily includes the power to regulate and protect wildlife living there, state law notwithstanding."
Lands held by the United States in trust for Native American tribes are generally not considered public lands. There are some 55 million acres of land held in trust by the federal government for Indian tribes and almost 11 million acres of land held in trust by the federal government for individual Natives. Although the United States holds "legal title" to these lands, the tribe or individual holds "beneficial title" (the right to use and benefit from the property). As a result, Indian Country is "quasi-private, not public, land." Nevertheless, "because the United States is a legal title holder, the federal government is a necessary part in all leases and dispositions of resources including trust land. For example, the secretary of the interior must approve any contract for payment or grant by an Indian tribe for services for the tribe 'relative to their lands' (25 U.S.C. § 81)."
History of U.S. federal lands.
The Land Ordinance of 1785 and the Northwest Ordinance of 1787 provided for the survey and settlement of the lands that the original 13 colonies ceded to the federal government after the American Revolution. As additional lands were acquired by the United States from Spain, France and other countries, the United States Congress directed that they be explored, surveyed, and made available for settlement. During the Revolutionary War, military bounty land was promised to soldiers who fought for the colonies. After the war, the Treaty of Paris of 1783, signed by the United States, the Kingdom of Great Britain, France, and Spain, ceded territory to the United States. In the 1780s, other states relinquished their own claims to land in modern-day Ohio. By this time, the United States needed revenue to function. Land was sold so that the government would have money to survive. In order to sell the land, surveys needed to be conducted. The Land Ordinance of 1785 instructed a geographer to oversee this work as undertaken by a group of surveyors. The first years of surveying were completed by trial and error; once the territory of Ohio had been surveyed, a modern public land survey system had been developed. In 1812, Congress established the General Land Office as part of the Department of the Treasury to oversee the disposition of these federal lands. By the early 1800s, promised bounty land claims were finally fulfilled.
In the 19th century, other bounty land and homestead laws were enacted to dispose of federal land. Several different types of patents existed. These include cash entry, credit, homestead, Indian, military warrants, mineral certificates, private land claims, railroads, state selections, swamps, town sites, and town lots. A system of local land offices spread throughout the territories, patenting land that was surveyed via the corresponding Office of the Surveyor General of a particular territory. This pattern gradually spread across the entire United States. The laws that spurred this system with the exception of the General Mining Law of 1872 and the Desert Land Act of 1877 have since been repealed or superseded.
In the early 20th century, Congress took additional steps toward recognizing the value of the assets on public lands and directed the Executive Branch to manage activities on the remaining public lands. The Mineral Leasing Act of 1920 allowed leasing, exploration, and production of selected commodities, such as coal, oil, gas, and sodium to take place on public lands. The Taylor Grazing Act of 1934 established the United States Grazing Service to manage the public rangelands by establishment of advisory boards that set grazing fees. The Oregon and California Revested Lands Sustained Yield Management Act of 1937, commonly referred as the O&C Act, required sustained yield management of the timberlands in western Oregon.
Sagebrush Rebellion movement in the Western United States in the 1970s and the 1980s sought major changes to federal land control, use, and disposal policy in 13 western states in which federal land holdings include between 20% and 85% of a state's area. Supporters of the movement wanted more state and local control over the lands, if not outright transfer of them to state and local authorities and/or 
Primary federal land holders.
The four primary federal land holders are:
The fifth largest federal landowner is the U.S. Department of Defense, which owns, leases, or possessed 26.1 million worldwide, of which 11.4 million acres are located in the United States. DOD land is mostly military bases and reservations. The largest single DOD-owned tract is the 2.3-million-acre White Sands Missile Range in New Mexico.
Together, the BLM, FWS, NPS, Forest Service, and DOD manage 97% of federal land. Federal agencies that control smaller amounts of land include the U.S. Army Corps of Engineers, the Bureau of Reclamation, the United States Postal Service, the National Aeronautics and Space Administration, and the U.S. Department of Energy.
Distribution and changes over time.
Federal land is concentrated in the Western United States. Nationwide, the federal government owns 27.4% of all land area. There are significant variations regionally; the federal government owns 61.3% of the land area in Alaska, 46.4% of the land area in the 11 contiguous Western states; and 4.2% of the land area of other states. The state with the highest percentage of land held by the federal government is Nevada (79.6%); the states with the lowest percentage of land held by the federal government are Connecticut and Iowa (0.3%).
From 1990 to 2015, federal acreage declined by about 3.9% due to a decline in land held by DOD and BLM.
Acquired lands.
In the United States, acquired lands refer to a category of public lands in federal ownership that were obtained by the federal government through purchase, condemnation, gift, or exchange.