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.
In 2015, about 897 million short tons of coal were produced in 25 states. Five states produced a total of about 639 million short tons, or about 71% of total U.S. coal production. The five largest coal producing states with production in million short tons and the share of total U.S. coal production in 2015: 1  Wyoming: 375.8 (42%) 2  West Virginia: 95.6 (11%) 3  Kentucky: 61.4 (7%) 4  Illinois: 56.1 (6%) 5  Pennsylvania: 50.0 (6%)