Covering some 900 square miles in Mercer, Wyoming, and McDowell counties in West Virginia, and neighboring Tazewell County, Virginia, the rich Pocahontas No. 3 coal seam was first mined by Jordan Nelson, whose backyard coalbank eventually attracted serious interest from the Philadelphia founders of the Norfolk & Western Railway. The N&W completed its line to the Pocahontas, Virginia, location of Nelson's coalbank in March 1883 and began the rapid industrialization of the region.

Largely owned by the N&W's Pocahontas Land Corporation, which leased mining rights to independent coal companies, the Pocahontas Coalfield has been one of the most productive in the nation. The low-volatile, low-sulfur, "smokeless" coal originated during the Lower and Middle Pennsylvanian Period and is older and better than most coal found elsewhere in the world. It stood 11 feet thick at Pocahontas, was perfect for making coke for use in steelmaking, and was the chosen fuel of the U.S. Navy during the age of steam. Of the original three billion tons in the field, some 900 million remain.

The exploitation of the Pocahontas No. 3 seam transformed southern West Virginia, creating the cities of Bluefield, Bramwell, Keystone, Northfork, Kimball, Welch, and Gary, and numerous coal company towns. The huge demand for miners in the labor-intensive early years created great racial and ethnic diversity. The U.S. Coal Commission's 1923 survey showed that 20,000 of West Virginia's 92,000 miners worked in the Pocahontas region. Twenty percent were foreign-born immigrants, 33 percent African-American, and the remainder native-born whites. The Pocahontas coalfield saw little of the endemic violence of the West Virginia Mine Wars, although union hero Sid Hatfield was assassinated on the steps of the McDowell County courthouse in Welch.