United States National Forests are largely forested and woodland areas 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 Department 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. National Forests fall under IUCN Protected Area Management Categories VI.

The national forest system was created by the Land Revision Act of 1891. It was the result of concerted action by Los Angeles-area businessmen and property owners who were concerned by the harm being done to the watershed of the San Gabriel Mountains by ranchers and miners. Abbot Kinney and forester Theodore Lukens were key spokesmen for the effort.

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, over-intensive logging, undervalued stumpage fees, antiquated mining laws and road-building in national forests.

In the USA there are 155 national forests containing almost 190,000,000 acres (297,000 mi² - 769 000 km²) of land. These lands comprise 8.5 percent of the total land area of the United States, an area about the size of Texas. Only 13 percent of National Forest land lies east of the Mississippi River. Alaska alone accounts for 12 percent 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 U.S. 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. U.S. citizens are allowed to camp anywhere in national forests as long as their campsite is at least 200 feet away from any roads or paths.