This article is on national forests in the United States. For the National Forest in England, see National Forest, England.

National forests are protected forests in the United States. National forests are controlled by the federal government and managed by the United States Forest Service, under the direction of the United States Secretary of Agriculture. The management of these lands focuses on timber harvesting, livestock grazing, water, wildlife, and recreation. Commercial use of national forests is permitted and in many cases encouraged, unlike national parks.

There are frequent conflicts between timber companies and environmentalists over the use of national forest land. These conflicts center on endangered species protection, logging of old-growth forests and road-building in national forests.

In the USA there are 155 national forests containing almost 190,000,000 acres (769,000 km²) of land. These lands comprise 8.5% of the total land area of the United States, an area about the size of Texas. Only 13% of National Forest land lies east of the Mississippi River. Alaska alone accounts for 12% of all National Forest land.

There are two distinctly different types of national forests. Those east of the Great Plains are primarily re-acquired or replanted forests. That is, the land had long been in the private domain but was purchased by the United States government in order to create new national forests. In these cases, the areas of national forest noted on most maps do not actually represent the extent of the national forest, but only the extent of the authorized purchase zone. The actual amount of land acquired in most cases is much smaller.

Those national forests west of the Great Plains are originally-owned forests. These are mostly lands reserved from the public domain by the US government, and were never in private hands. In these cases, the areas of national forests noted on maps are generally the true areas of the forest.

Many ski resorts operate in national forests.

The Forest Service also administers National Grasslands.

See also the list of U.S. national forests.