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.
Total US coal production, 1870-2011. Coal mining in the United States is a major industry, coal being mined in 25 states, 40% on public lands. Mined tonnage reached an all-time high of 1.06 Gt (1.17 billion short tons) in 2008, but by 2015 had declined to 986 million short tons.