The Department of the Interior

The National Park Service manages 400-plus park units, including 63 sites carrying the formal designation 'National Park,' from Yellowstone to the Grand Canyon, along with national monuments, historic sites, and battlefields, drawing more than 300 million visitors each year, more than the combined attendance of every major American professional sports league.

Created in 1916 with a dual mission that requires the agency to both preserve park resources unimpaired for future generations and make them accessible to the public today, a balancing act that generates recurring policy debates over development, overcrowding, and conservation funding.

The service has about 20,000 permanent and seasonal employees plus hundreds of thousands of volunteers, and its parks span more than 85 million acres. It also runs the National Register of Historic Places and administers preservation grants and the Historic Preservation Tax Incentives program.

It carries a deferred-maintenance backlog long estimated at more than $20 billion, for roads, trails, water systems, and historic buildings; the 2020 Great American Outdoors Act created a dedicated fund, drawn from energy revenue, to work it down over five years.

The Bureau of Indian Affairs administers the federal government's trust responsibilities to the 574 federally recognized tribes, managing tribal trust lands and natural resources, funding tribal governments and social services, and overseeing law enforcement on many reservations through the Bureau of Indian Affairs Office of Justice Services.

The bureau's relationship with tribal nations is grounded in treaties, federal statutes, and the unique legal doctrine of tribal sovereignty, which recognizes tribes as distinct governments with a government-to-government relationship to the United States rather than simply another category of domestic constituency.

The BIA is one of the oldest federal agencies, established within the War Department in 1824 and moved to the new Interior Department in 1849. Its history includes running the boarding-school system that forcibly assimilated Native children, a legacy Interior's Federal Indian Boarding School Initiative formally documented; its 2024 final report identified 417 such schools and at least 973 child deaths.

The related Bureau of Indian Education funds or operates 183 schools serving about 46,000 students, and the Bureau of Trust Funds Administration manages tens of billions of dollars in tribal and individual Indian trust accounts, the subject of the long-running Cobell litigation that the government settled for $3.4 billion in 2010.

The Bureau of Land Management oversees roughly 245 million acres of public land, more than any other federal agency, managing grazing leases, mining and energy development, recreation, and wildlife habitat under a 'multiple use' mandate that requires balancing competing demands on the same land.

The agency manages the vast majority of federal land in the western United States, where BLM parcels are frequently interspersed with private and state land in a checkerboard pattern that dates back to 19th-century railroad land grants, complicating land-use planning to this day.

Its "multiple use and sustained yield" mandate comes from the Federal Land Policy and Management Act of 1976, which ended the era of routinely selling off public land and directed the BLM to keep most of it in federal hands and plan its uses. It also manages about 700 million acres of subsurface mineral rights beneath land owned by others.

The BLM administers the 1872 General Mining Law, which still lets prospectors stake hardrock claims for gold, silver, copper, and lithium with no federal royalty, a rule critics have tried to change for decades. It also runs the wild horse and burro program, which manages tens of thousands of animals on the range and in holding facilities.

The Fish and Wildlife Service administers the Endangered Species Act, protecting more than 1,600 species listed as threatened or endangered, and manages the National Wildlife Refuge System, which spans more than 850 million acres of land and water dedicated to conservation.

The agency is widely credited with the recovery of iconic species including the bald eagle, which was removed from the endangered species list in 2007 after decades of protection, though it remains protected under separate federal laws specific to eagles.

It also enforces the Migratory Bird Treaty Act of 1918 and the Lacey Act against wildlife trafficking, runs national fish hatcheries, and administers the Duck Stamp, a hunting-license stamp whose sales have funded the purchase of millions of acres of wetland refuge since 1934.

Refuge System revenue is boosted by the Pittman-Robertson Act of 1937, an excise tax on firearms and ammunition that channels hundreds of millions of dollars a year to state wildlife agencies, one of the earliest and most durable "user pays" conservation funding models in the country.

Interior Secretary Albert Fall secretly leased Navy petroleum reserves at Teapot Dome, Wyoming to private oil companies in exchange for personal bribes, a scandal that led to Fall's conviction, making him the first Cabinet secretary in U.S. history imprisoned for actions taken in office.

The scandal prompted lasting reforms to how federal officials handle public land leasing decisions and remained the standard reference point for government corruption in American politics until the Watergate scandal five decades later eclipsed it in public memory.

Fall had persuaded President Harding to transfer the reserves from the Navy to Interior, then leased Teapot Dome to Harry Sinclair and the Elk Hills reserve in California to Edward Doheny without competitive bidding, in exchange for roughly $400,000 in cash and cattle disguised as a "loan."

The Supreme Court voided the leases in 1927, holding they had been obtained by fraud. The affair produced McGrain v. Daugherty (1927), a landmark ruling affirming Congress's power to compel testimony in investigations, a precedent still cited in modern subpoena fights.

The Dust Bowl of the 1930s, a severe drought and soil erosion crisis across the Great Plains, prompted the Interior Department and other federal agencies to launch major land conservation and soil management programs, reshaping federal land-use policy for decades afterward.

The crisis drove home the consequences of unsustainable agricultural practices on marginal public and private lands, and it directly influenced the creation of federal soil conservation programs that continue to guide how the Bureau of Land Management approaches rangeland health today.

The Taylor Grazing Act of 1934, administered by an Interior agency that later became part of the BLM, ended the open, unregulated grazing of the public domain by creating grazing districts, permits, and fees, the framework still in use on about 155 million acres of BLM rangeland.

Interior Secretary Harold Ickes, who held the job for a record 13 years under Franklin Roosevelt, also ran the Public Works Administration and pushed large dam and irrigation projects, expanding the Bureau of Reclamation's role in the West at the same time.

The Standing Rock Sioux Tribe's 2016 protests against the Dakota Access Pipeline, which was routed near tribal water sources and land the tribe considers sacred, drew national attention to the Interior Department's role in balancing energy development against tribal sovereignty and environmental concerns.

The dispute, which involved the Army Corps of Engineers' permitting authority as much as the Interior Department's own jurisdiction, became a landmark moment in the broader national conversation about tribal consultation requirements in federal infrastructure and energy permitting decisions.

Thousands of people, including members of hundreds of tribes, camped near the site for months. In December 2016 the Obama administration declined to grant the final easement and ordered a full environmental review; the incoming administration reversed that in early 2017 and the pipeline began operating.

A federal court later found the environmental review inadequate and, in 2020, ordered the pipeline emptied pending a new one, before an appeals court allowed oil to keep flowing while the review proceeded. The case is frequently cited in debates over the National Environmental Policy Act and tribal consultation.

Created in 1965 and funded largely through royalties paid by offshore oil and gas drilling, this fund has provided billions of dollars to acquire and protect parkland and support outdoor recreation projects in nearly every county in the country, from national parks down to local neighborhood playgrounds.

Congress permanently and fully funded the program at $900 million annually starting in 2020 through the Great American Outdoors Act, ending decades of inconsistent, year-to-year funding battles that had previously left much of its authorized funding diverted to other purposes.

The design is deliberate: revenue from the depletion of one public resource, offshore oil, is reinvested in permanent public assets, parks and recreation land. About half the money historically goes to federal land acquisition and half to matching grants for state and local parks.

Since 1965 the fund has supported projects in more than 98 percent of U.S. counties, and its state-grant side has helped build or improve tens of thousands of local ballfields, trails, and swimming pools that most users never connect to a federal program.

The Bureau of Ocean Energy Management leases federal offshore areas for oil, gas, and, increasingly, wind energy development, generating billions of dollars in royalty revenue for the federal treasury and coastal states while managing the environmental review process required before drilling or construction can begin.

Offshore leasing policy shifts significantly between administrations, with recent years seeing expanded leasing for oil and gas alongside a rapidly growing federal offshore wind program intended to supply power to East Coast population centers.

The federal offshore area, the Outer Continental Shelf, is governed by a 1953 law and produces roughly 15 percent of U.S. crude oil, almost all of it from the Gulf of Mexico; Pacific, Atlantic, and eastern Gulf waters have been under leasing moratoriums for decades. A companion safety agency, the Bureau of Safety and Environmental Enforcement, was split off after the 2010 Deepwater Horizon blowout, which killed 11 workers and caused the largest marine oil spill in U.S. history.

The first commercial-scale U.S. offshore wind farms began delivering power off the Northeast in the mid-2020s, and BOEM has held lease auctions raising billions of dollars for wind areas off the Atlantic, Gulf, and California coasts.

The U.S. Geological Survey operates the nation's earthquake, volcano, and streamflow monitoring networks, providing the real-time data that powers earthquake early-warning alerts, volcano eruption forecasts, and flood predictions used by emergency managers across the country.

USGS scientists also maintain the long-term water and mineral resource data the country relies on for everything from urban water planning to assessing the domestic supply of critical minerals needed for defense and clean energy technology.

The agency runs about 8,000 streamgages, the ShakeAlert earthquake early-warning system now live on the West Coast, and volcano observatories in Alaska, the Cascades, Yellowstone, Hawaii, and California. It is the science agency of the department and does no regulation itself.

USGS also produces the National Seismic Hazard Maps that underlie building codes, publishes the annual Mineral Commodity Summaries that track U.S. import reliance on materials like rare earths, and makes the Landsat satellite imagery archive freely available, an early and influential open-data program.

Federal law and executive orders require Interior and other agencies to formally consult with tribal governments before taking actions that could affect tribal lands, resources, or treaty rights, a process meant to give tribes a meaningful voice in decisions ranging from pipeline permits to national monument designations.

The consultation requirement has become an increasingly prominent feature of major infrastructure and energy project reviews, and disputes over whether consultation was conducted adequately have repeatedly ended up in federal court in recent years.

The current framework rests on Executive Order 13175 (2000), which every administration since has reaffirmed, plus statutes such as the National Historic Preservation Act and the Native American Graves Protection and Repatriation Act of 1990. Consultation is a process obligation, not a veto: agencies must seek tribal input in good faith but can still proceed over tribal objection.

Recent practice has expanded to recognizing tribal "Indigenous Knowledge" in federal science and land decisions and to co-stewardship agreements letting tribes help manage ancestral lands now inside national parks, forests, and monuments such as Bears Ears in Utah.