More than 90 percent of all coal mines in Colorado have been underground mines. Coal mining in the 1800s actually began in coal seams near Golden that were vertical. This involved shaft mining in coal or clay from the surface, then drifting through stable sandstone beds and mining upward in the coal bedto remove the coal. When it was too deep to mine, they would drift over to horizontal seams to the east. Coal mines in the Boulder-Erie-Louisville-Lafayette area then mined deeper coal by constructing vertical shafts and hoisting the coal out. This worked until the era of conventional mechanized coal mining began in 1943 when underground miners could leave their picks for good.
Conventional miners removed coal by digging into the coal and then shuttle cars and conveyors hauled the coal to the surface.By the 1970s longwall mining machines were developed toremotely remove large blocks of coal safely without fear of major roof falls or collapse. Today most large-scale mining is done with longwall operations, the main reason for increased safety in modern underground mining. There are five (5) longwalls operating in Colorado coal mines today at Twentymile Mine, Deserado Mine, Bowie Mine, Elk Creek Mine, and West Elk Mine. In 2010 over 20 million tons of coal were mined at the state’s seven (7) underground coal mines. There are 1,635 underground coal miners employed in Colorado today. The Peabody Energy Foidel Creek (Twentymile) Mine in Routt Countyis the nation’s fourth largest underground coal mine. Coal is mined as deep as 2,700 ft in Colorado.