The massacre could not stop the coal boom. According to the WMA, in 1917 mines in Wyoming produced 8,456,664 tons of coal. The importance of mining for Wyoming becomes clear by taking a look at the state's Constitution. Article nine deals with the establishment of the office of the inspector of mines, damages for injuries of miners and the state's obligation to provide a school of mines and proper development, ventilation, drainage and operation of all mines in the state. In the 1920s surface mining started to replace the traditional underground coal mining.
Surface mining is more economic.
In surface mining one worker can mine what 10 workers mined in an underground facility. Today the only underground mines that are left in Wyoming are the trona mines around Green River, Loomis said. The 1950s saw a stagnation of the coal mining industry, because the railroad did not need coal anymore. According to WMA data, Wyoming produced only 2.5 million tons of coal in 1957. In the 1970s the federal government passed new clean air standards.