Mechanization of West Virginia's coal mines took place gradually throughout the first half of the 20th century. Traditionally, coal mining involved the distinct steps of undercutting the seam, then drilling and blasting the undercut coal into manageable pieces, and finally loading and hauling the coal to the surface. The complexity of these tasks and the tight spaces encountered underground, especially in low-coal seams, presented difficult challenges for inventors of mine machinery. Consequently, mechanization first influenced surface activities such as pumping the water from the mines, as well as hoisting and ventilation, and these advances enabled operators to drastically increase the physical scope of their underground operations. The appropriate power source proved critical to underground mechanization, and by the turn of the 20th century the versatility of electricity made it more attractive than steam or compressed air.

Underground mechanization first centered on haulage and undercutting. By the early 1900s, trolley-operated locomotives (often called "motors" by miners) replaced animal power for main-line haulage. Mules remained important for transport of mine cars to and from the working face to the main line until the 1920s, when cable-reel locomotives displaced them. By 1900, several types of undercutting machines eliminated the time-consuming task of undercutting by pick. However, miners continued to drill, blast, and load manually, and control of these critical skills enabled them to maintain much of their independence at the working face. Unfortunately, the large amount of coal dust, created by the new cutting machines and distributed throughout the mine by mechanized ventilation, increased the probability of explosions.

In the 1920s, the mechanized car-loading conveyor increased the hand loaders' efficiency by lowering the height for shoveling and streamlining the transport of coal. Their versatility in difficult mining conditions made hand-loaded conveyors popular in West Virginia, and some large operations relied on them into the 1950s. However, the innovation that would replace conveyors and bring an end to the hand-loading era also made its appearance in the 1920s: the mobile coal-loading machine.

Miners tended to resist mechanization, but United Mine Workers President John L. Lewis saw it as a means of increasing tonnage per worker and, subsequently, individual pay. Unionism in turn raised labor costs and encouraged operators to embrace full mechanization. By the late 1940s, mobile loading machines, particularly the Joy loader, combined with power drills, cutting machines, and conveyors or shuttle cars to drastically alter the traditional mining process. Much of the miners' traditional independence in the workplace dissolved as they ceased to be skilled workers and instead became hourly workers assembled into teams of machine operators led by a foreman. This mechanization of the working face dramatically increased tonnage per worker and displaced thousands of miners.

By the 1950s, the roof-bolter, or pinner, replaced the timbering system, clearing passageways and eliminating obstacles to the movement of machinery. The continuous-mining machine—which finally synthesized all the steps of hand mining into one phase—and continuous-belting for coal transport further reduced labor requirements, expanding the exodus of former miners to northern industrial centers.

Producing ten times the coal with half the workers, longwall-mining machinery increased in popularity in the 1970s. Eliminating the need for driving rooms and pillaring, longwall "plows" or "shears" dislodged coal from the face of an entire panel into an automatically advancing conveyor system. With longwall and other modern methods, West Virginia at the opening of the 21st century produces the most coal in its history, but with fewer miners than ever.