production of crushed rock aggregate

Jun 16, 2014 · The combined production of the 10 leading states increased slightly from 2011 to 669 million short tons, more than one-half of the national total. In 2012, underground production, totaling 78 million short tons, accounted for 6 percent of the U.S. production of crushed stone. Crushed stone was produced in 85 underground mines in 18 states.