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.
US coal production has declined since 2008, with 896 million short tons produced in 2015, the lowest since 1986. Top ten coal-mining companies in the United States, 2014. In 2014, the production owned by the top ten companies was 72.6% of total US coal production.