The Interior Department manages America's public lands and natural resources, roughly 500 million acres, an area larger than Alaska and Texas combined, including national parks, wildlife refuges, and land overseen by the Bureau of Land Management. It also manages offshore energy leasing in federal waters and the natural resources beneath public lands.

A significant part of the department's mission involves its government-to-government relationship with 574 federally recognized Native American tribes, administered through the Bureau of Indian Affairs, which manages tribal trust lands, funds tribal governments, and oversees federal treaty obligations dating back over a century.

The department also runs the National Park Service, which welcomes more than 300 million visitors annually across 400-plus park units, the U.S. Fish and Wildlife Service, which protects endangered species and migratory birds, and the U.S. Geological Survey, which monitors earthquakes, volcanoes, and the nation's water resources.