Boise National Forest, National Forest in Idaho, United States.

Boise National Forest covers 2,203,703 acres of central Idaho, managed as five ranger districts: Cascade, Emmett, Idaho City, Lowman and Mountain Home. The Idaho Batholith underlies most of it, forming the Boise, Salmon River and West mountain ranges, which reach 9,730 feet on Steel Mountain. Sagebrush steppe and spruce-fir forests cover the slopes, cut by 9,600 miles of streams and rivers and holding 15,400 acres of lakes and reservoirs.

The forest was established in 1908 when it was separated from the original Sawtooth National Forest to create a distinct protected area. Gold mining became a major activity through the early and mid-twentieth century before operations eventually declined.

The Shoshone occupied the land before European settlers arrived in the early 19th century, and archaeological sites along its rivers include campsites, rock shelters, burial grounds and pictographs. The forest's name comes from the Boise River; French-Canadian trappers called it la rivière boisée, "the wooded river", which English speakers shortened to Boise.

Boise National Forest is managed as five ranger districts: Cascade, Emmett, Idaho City, Lowman and Mountain Home, so orientation starts with choosing a district. The forest holds over 70 campgrounds and 1,300 miles of trails for hiking, biking, horseback riding and off-road vehicles. Steel Mountain reaches 9,730 feet, and the forest has 9,600 miles of streams and rivers plus 15,400 acres of lakes and reservoirs.

Sacajawea's bitterroot, a flowering plant endemic to Idaho, is known from few places outside this forest: 75 percent of its documented populations lie within Boise National Forest. The plant grows on the forest's sagebrush steppe and open slopes, and botanists survey its stands there.