Monongahela National Forest was established following passage of the 1911 Weeks Act, which authorized the federal purchase of land for long-term watershed protection, forest restoration, and natural resource management.

In 1915, 7,200 acres in the mountains near Parsons, West Virginia, were acquired by the federal government and called the Monongahela Purchase. Monongahela National Forest was officially designated April 28, 1920, incorporating the original purchase tract. Over the years, additional lands were acquired within the 1.7 million-acre proclamation boundary of the Forest. Today, the Forest includes more than 919,000 acres in 10 counties in the West Virginia highlands.

The Monongahela National Forest is considered by The Nature Conservancy to be in an area of global ecological importance. Much of this diversity can be attributed to the wide variations in elevation and the resulting patterns of precipitation. 

Most of the weather patterns approach the Forest from the west where they are forced up and over the Appalachian Mountains that form the spine of Monongahela National Forest. The western side of the Forest receives about 60 inches of precipitation per year while the "rain shadow" side on the east receives half of that.

The Forest’s mountain ranges mostly lie in a northeast to southwest pattern. The lowest part of the Forest is on the eastern side and is about 1,000 feet above sea level, while the central portion of the Forest includes Spruce Knob, the state's highest peak, at 4,863 feet. Rivers and streams throughout the Forest act as a travel corridor for both plants and animals. Elevation changes on the slope of a single mountain ridge cause micro-climates as indicated by vegetation ranges.

The biological complexity is evident — at least 75 tree species; more than 225 bird species; 8 federally-listed, threatened or endangered bird, bat, salamander, and plant species; 60 nongame/forage fish species; 12 game fish species; and numerous other wildlife species inhabit the Forest.

The natural resources of the Forest have a wide number of uses, ranging from extensive recreational opportunities to timber harvesting, from livestock grazing to mineral extraction, and from clean drinking water to a relaxing getaway destination.