Preliminary data released by the U.S. Department of Labor’s Mine Safety and Health Administration (MSHA) indicates that 40 miners died in work-related accidents at the nation’s mines in 2014, two fewer than in the previous year. Coal mining deaths dropped from 20 in 2013 to 16 in 2014, the lowest annual number of coal mining deaths ever recorded in the United States. The previous record low was 18 in 2009.

While the numbers of coal mines and miners have recently declined, the number of deaths in 2014 is about half what the industry experienced in the early 2000’s, when the numbers of working coal miners were at comparable levels.

Twenty-four deaths occurred in metal and nonmetal mines last year, an increase from 22 deaths in 2013.

The most common causes of mining accidents in 2014 involved powered haulage and machinery; five powered haulage and five machinery related deaths occurred in coal mines, and powered haulage accounted for eight deaths in metal and nonmetal mining. Powered haulage accidents involve equipment used to transport people, materials or supplies, and machinery accidents are associated with the action or motion of machinery or failure of component parts.