The concept of securitization is generally associated with the Copenhagen school of security studies, which is generally taken to include Ole WÃ¦ver, Barry Buzan, and a range of other, more loosely associated, researchers.
Average annual number of employed coal miners in the United States, 1890-2014. US employment in coal mining peaked in 1923, when there were 863,000 coal miners. Since then, mechanization has greatly improved productivity in coal mining, so that employment has declined at the same time coal production increased. The average number of coal mining employees declined to 65,400 in 2015.
Coal is mined in 32 states. The three major U.S. coal producing regions are Appalachia (West Virginia, Pennsylvania, Virginia, Eastern Kentucky, and Ohio), the Illinois Basin (Illinois, Indiana and Western Kentucky) and the Powder River Basin (Wyoming and Montana).