The Humboldt–Toiyabe National Forest (HTNF) is the principal U.S. National Forest in the U.S. state of Nevada, and has a smaller portion further west in Eastern California in the state of California. With an area of 6,289,821 acres (25,454.00 km), it is the largest U.S. National Forest reservation outside of Alaska, further northwest on the North American continent.

The lands now part of Humboldt-Toiyabe have been administratively reorganized many times, and include parts of several defunct national forests. The oldest of these is the Ruby Mountains National Forest, established on May 3, 1906 during the presidential administration of the famed "conservationist president" of 26th President Theodore Roosevelt (1858-1919, served 1901-1909). Two years later in 1908, it was combined with the Independence National Forest to form Humboldt National Forest. Then the Toiyabe National Forest was established a year earlier on March 2, 1907. It ceased to exist a quarter-century later in 1932, when it was absorbed by the Nevada National Forest, but was reestablished only six years afterwards in 1938 from parts of Humboldt and Nevada forest reserves. The last major reorganization of American government forest reserves in the state, occurred on October 1, 1957, during the Dwight D. Eisenhower (1890-1969) presidential administration of the former United States Army commanding general from World War II and 34th President. He served in the White House 1953-1961, when the older Nevada National Forest was dissolved and its lands divided between Humboldt and Toiyabe reserves.

Humboldt and Toiyabe National Forests were administratively joined almost four decades later in 1995, during Bill Clinton's two terms as 42nd President from 1993-2001. Although managed since as a single entity, the two forests remain legally and geographically separated and distinct.

HTNF is unlike most other national forests as it contains numerous non-contiguous sections scattered across most of the state of Nevada and a portion of adjacent eastern California to the west. Seven park ranger districts are located in the many mountain ranges in Nevada, from the Santa Rosa Range in the north to the Spring Mountains near Las Vegas in the south. About 11% of the forest is in eastern California, in the areas around Bridgeport and Markleeville, and other areas west of the Sierra Nevada mountain chain between the two states.

The national forest lies in 13 counties in Nevada and 6 in California. The counties with the largest amount of federal forest land are Nye, Elko, and White Pine in Nevada, and Mono County in California, but there are also 15 other counties represented with land in this widely dispersed national forest reserve. Forest headquarters are located in the small city of Sparks, Nevada, near Reno, the largest city and county seat of Washoe County in the northwestern corner of the state, along the Nevada-California state line.

The smaller and more northeasterly Humboldt National Forest is located in eastern and northern Nevada, in parts of Elko, White Pine, Humboldt, Nye, and Lincoln counties. The section of the national forest is named after Alexander von Humboldt (1769-1859), a famous early / mid-19th century Prussian / German multi-talented scientist and philosopher. Born and raised / educated in Europe, although he traveled extensively in the Americas / Western Hemisphere in 1799-1804, exploring and doing various fields of scientific research. and contains about 43.5% of the total area. Local National Park ranger / United States Park Police district offices are located in four towns: Ely, Elko, Wells, and Winnemucca of Nevada.

The larger and more southwesterly Toiyabe National Forest is located in central, western, and southern Nevada and eastern California, in parts of Nye, Lander, Mineral, Lyon, Eureka, Washoe, Douglas, and Clark counties, and the state capital of Carson City in the "Battle Born State" of Nevada; as well as in the adjacent "Golden State" with Mono, Alpine, Sierra, Nevada, Lassen, and El Dorado counties in the state of California. Toiyabe is a Native American name. The section contains about 56.5% of the total area. Local ranger district offices are located in the towns / cities of Austin, Bridgeport, Carson City, Las Vegas, and Tonopah. Bridgeport is the only station that is in California.

• Austin Ranger District – around Austin, including Shoshone Mountains
• Bridgeport Ranger District – around Bridgeport
• Carson Ranger District – near Carson City
• Ely Ranger District – around Ely, Nevada
• Jarbidge Ranger District – near Jarbidge
• Mountain City Ranger District – near Mountain City
• Ruby Mountains Ranger District – Ruby Mountains and East Humboldt Range

(formerly Ruby Mountains National Forest)

• Spring Mountains National Recreation Area – Spring Mountains
• Santa Rosa Ranger District – Santa Rosa Range
• Tonopah Ranger District – near Tonopah, Nevada, including Toiyabe Range, Toquima Range, Monitor Range, and Hot Creek Range

• Wovoka Wilderness

In descending order of forest land area within the counties:

• Nye, Elko, White Pine, Lander, Humboldt, Mineral, Lyon, Eureka, Washoe, Douglas, Clark, Lincoln, Carson City

• Mono County, Alpine, Sierra, Nevada, Lassen, El Dorado

• List of national forests of the United States

• Official website
• National Atlas: Map of Humboldt–Toiyabe National Forest