Mark Twain National Forest (MTNF) is a U.S. National Forest located in the southern half of Missouri, composed of nine disconnected parcels. MTNF was established on September 11, 1939. It is named for author Mark Twain, a Missouri native. The MTNF covers 3,068,800 acres (12,419 km2) of which 1,506,100 acres (6,095 km2) is public owned, 78,000 acres (320 km2) of which are Wilderness, and National Scenic River area. MTNF spans 29 counties and represents 11% of all forested land in Missouri. MTNF's nine tracts are divided into six distinct ranger districts: Ava-Cassville-Willow Springs, Eleven Point, Houston-Rolla, Cedar Creek, Poplar Bluff, Potosi-Fredericktown, and the Salem. Its headquarters are in Rolla, Missouri.

Rolla is a city in, and the county seat of, Phelps County, Missouri, United States. Its population in the 2020 United States Census was 19,943. It is approximately midway between St. Louis and Springfield along I-44. Its micropolitan statistical area consists of Phelps County, Missouri.