Drift mining is either the mining of an ore deposit by underground methods, or the working of coal seams accessed by adits driven into the surface outcrop of the coal bed. A drift mine is an underground mine in which the entry or access is above water level and generally on the slope of a hill, driven horizontally into the ore seam.
Drift is a more general mining term, meaning a near-horizontal passageway in a mine, following the bed (of coal, for instance) or vein of ore. A drift may or may not intersect the ground surface. A drift follows the vein, as distinguished from a crosscut that intersects it, or a level or gallery, which may do either. All horizontal or subhorizontal development openings made in a mine have the generic name of drift. These are simply tunnels made in the rock, with a size and shape depending on their use—for example, haulage, ventilation, or exploration.
Historical US drift mining (coal)
Colorado
The Boulder-Weld Coal Field beneath Marshall Mesa in Boulder, Colorado was drift mined from 1863 to 1939. Measurements in 2003, 2005, and 2022 showed that the mine has an active coal-seam fire. It was investigated as a possible cause of the 2021 Marshall Fire.
Illinois
Argyle Lake State Park's website says the Argyle Hollow (occupied by a lake since 1948) has been rich in coal, clay and limestone resources. Historically, individuals commonly opened and dug their own "drift mines" to supplement their income. In Appalachia, small coal mining operations such as these were known as "country bank" or "farmer" coal mines, and usually produced only small quantities for local use.
Indiana
The Lusk Mine, now in Turkey Run State Park, was in operation from the late 1800s through the late 1920s. Too small for commercial operation, the mine probably provided coal for the Lusk family and later for the park.
Kentucky
In 1820 the first commercial mine in Kentucky, known as the "McLean drift bank" opened near the Green River and Paradise in Muhlenberg County. In Drift, Kentucky, Beaver Coal & Mining Company was the most well known operator of mines, but there were other smaller mines (Floyd-Elkhorn Consolidated Collieries, Turner-Elkhorn Coal Company, etc.) as well.
Maryland
Dorsey Coal Company's Ashby coal mine, a small drift mine probably in the Upper Freeport coal; and the mine of the Taylor-Offutt Coal Company near Oakland, MD.
Ohio
In the 1880s, State Inspector of Mines, Andrew Roy, issued a report on the Mines and Mining Resources of Ohio, which includes the following paragraphs:
Pennsylvania
Indiana County: Graff Drift Mines, near Blairsville. Commodore Mines, Nos. 1 & 3 (drift mines), No. 2 (slope mine), Green Twp. Empire "F" Mine (1910-?), Shanktown; a drift mine, mining the "B" coal seam, mining done by machine, owner Pioneer Coal Company, Clearfield. Empire "M" Mine (McKean Mine) (1906-?), a drift mine, non-gaseous, mining a 38" thick seam of Lower Kittaning coal using compressed air machines; ventilation provided by an 8' Stine steam-powered fan, Clymer, PA. Rodkey Mine(1906-?), a drift mine, Clymer. Ernest Mine No. 2 (1903-1965), a drift mine, at Ernest, Rayne Twp., Indiana Co., PA.
Tennessee
The Fork Mountain, TN, drift portal entered an 84-inch unnamed seam of coal (see picture above). Most coal seams in Tennessee were not this thick.
Virginia
The first coal mine in the Pocahontas Coalfield with its famous 13 feet tall seam of Pocahontas No. 3 coal, the Pocahontas mine is a drift mine.
West Virginia
Many, many references to and photographs of WV drift mines in the Scrapbook of Appalachian Coal Towns, including Sprague, Kaymoor, Nuttallburg, Venus, Layland, Elverton, Casselman (aka Castleman), etc.
Historical US drift mining (gold)
Alaska
Drift mining methods were used extensively to mine placer deposits during the early years (1899- ) of the Nome mining district. During summer, surface deposits could be worked, but some placer deposits were buried too deeply for surface placering. In addition, water to wash the gold from the placers was not available in the winter. Many miners tunneled into deep placer deposits, bringing out the high-grade gravels to be washed at the spring thaw. Most of the ground in Nome is permafrost. By drift mining, miners were able to recover much of the gold buried under the permafrost.