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.
But coal mining is a highly concentrated extractive industry. Only 53 large U.S. coal mines account for about 60% of total U.S. coal output. Eastern Coal. Three states alone â Pennsylvania, Kentucky and West Virginia â produce 52% of the high-quality thermal and metallurgical coal in the U.S. Coal output in all three of these states has been flat or in decline for many years.