[3] Harrison County is part of the Clarksburg, WV Micropolitan Statistical Area.

Indigenous peoples have lived in the area that would become Harrison County for thousands of years.

The Virginia Colony claimed the area as part of its vast Augusta County.

The first permanent settler in the area was hunter and trapper John Simpson, who erected a cabin at the mouth of Elk Creek on the West Fork River in 1763 or '64.

According to a 19th-century local historian, he ... ... continued to hunt and trap for a year without encountering any other human being.

In 1765, he went to the South Branch to dispose of a stock of skins and furs, and returning to his camp, remained until permanent settlements were made in the vicinity.

... Simpson's cabin was located about one mile from Clarksburg, on the west side of the West Fork River ... Simpson became indebted to a man named Cottrial[9] to the amount of "one quart of salt" (a precious article at the time), which he agreed to pay, either in money or salt, upon his return from Winchester, whither he was going to dispose of a stock of skins and furs.

Upon his return, a dispute arose between them, regarding the payment, and Cottrial, in the heat of passion, hastened from the house, and grasping Daniel Davisson's gun, which stood leaning against the cabin, took aim through the space between the logs, and attempted to shoot Simpson.

[12] The first meeting of the Harrison County court was held on July 20, 1784, at the home of George Jackson.

The railroad was instrumental to the development of the local coal mining industry during the late 1800s and early 1900s.

In 1863, West Virginia's counties were divided into civil townships, with the intention of encouraging local government.

This proved impractical in the heavily rural state, and in 1872 the townships were converted into magisterial districts.

[14] Harrison County was divided into ten districts: Clark, Clay, Coal, Eagle, Elk, Grant, Sardis, Simpson, Tenmile,[i] and Union.

[15] The county terrain consists of low rolling hills, is largely wooded, and etched by drainages and creeks.

[30] Adjacent to Charles Pointe, the United Hospital Center, a $278 million state-of-the-art medical facility.

[31] Across from the United Hospital Center site, White Oaks, a planned business community is also under construction, and will support the hospital and the FBI CJIS complex, which is also located near the White Oaks site.

[32][33] This area of West Virginia's Interstate 79 is considered part of a "High Tech Corridor.