Klamath National Forest, National forest in Siskiyou County and Jackson County, United States.

Klamath National Forest covers 1,737,774 acres in the Klamath Mountains and Cascade Range, mostly in Siskiyou County, California, with about 1.5 percent reaching into Jackson County, Oregon. Its slopes carry ponderosa and Jeffrey pine, Douglas fir, red and white fir, lodgepole pine, Baker cypress and incense cedar, and roughly 168,000 acres are old growth. Headquarters are in Yreka, with ranger district offices in Fort Jones, Happy Camp and Macdoel.

The forest was established in 1905 by the United States Forest Service to protect natural resources and support sustainable forestry. Since then, management has focused on balancing conservation with responsible land use.

The Karuk, Yurok, and Modoc peoples have deep roots here and continue to hold this land as sacred for their traditional ways. Visitors walking through the forest pass through places that remain spiritually and culturally important to these communities today.

The forest maintains over 900 miles of marked trails reached from ranger stations in Fort Jones, Happy Camp, and Macdoel, with maps available at visitor centers. Planning ahead for changing elevations and weather conditions makes for a safer and more enjoyable visit.

Four designated wilderness areas lie within the forest: Marble Mountain, Russian, Red Buttes and Siskiyou, the last shared with Six Rivers National Forest. Between the late 1980s and 2010 the Klamath Forest Alliance fought timber sales and roadless-area cases here, part of the region's timber wars.