List of national forests of the United States

The United States has 154 protected areas known as national forests, covering 188336179 acre. National forests are managed by the U.S. Forest Service, an agency of the U.S. Department of Agriculture. The first national forest was established as the Yellowstone Park Timber and Land Reserve on March 30, 1891, then in the Department of the Interior. In 1897, the Organic Act provided purposes for which forest reserves could be established, including to reserve a supply of timber, protect the forest from development, and secure water supplies. With the Forest Reserve Act of 1891, the president of the United States is given the power to set aside forest reserves in the public domain. With the Transfer Act of 1905, forest reserves became part of the U.S. Department of Agriculture in the newly created U.S. Forest Service.

By 1907, President Theodore Roosevelt had more than doubled the forest-reserve acreage, and Congress responded by limiting the president's ability to proclaim new reserves. The National Forest System underwent a major reorganization in 1908, and in 1911 Congress authorized new additions to the system under the authority of the Weeks Act. The management goals provided by the Organic Act were expanded upon by the Multiple-Use Sustained-Yield Act of 1960 to include "outdoor recreation, range, timber, watershed, and wildlife and fish purposes" as well as for the establishment of wilderness areas.

As of September 30, 2014, the Forest Service manages a total of 192922127 acre, 188336179 acre of which are national forests. The additional land areas include 20 national grasslands, 59 purchase units, 19 research and experimental areas, five land utilization projects and 37 other areas. The National Forest System has an extensive and complicated history of reorganization, so while there are currently 154 named national forests, many of these are managed together as either a single forest or separate forests.

There is at least one national forest in all but ten states: Connecticut, Delaware, Hawaii, Iowa, Kansas, Maryland, Massachusetts, New Jersey, North Dakota, and Rhode Island (although Kansas and North Dakota have national grasslands). In addition, Puerto Rico contains El Yunque National Forest, the only tropical U.S. rainforest. Alaska has the most national forest land, with 21.9 e6acre, followed by California (20.8 e6acre) and Idaho (20.4 e6acre). Idaho also has the greatest percent of its land in national forests, with 38.2 percent, followed by Oregon (24.7 percent) and Colorado (20.9 percent). On maps, national forests in the west generally show the true extent of their area, but those in the east often only show purchase districts, within which usually only a minority of the land is owned by the Forest Service.