The opening of fewer new coal mines, combined with the closing of less-efficient mines, led to 2013 having the lowest number of active coal mines in the U.S. on record, according to an analysis by the Energy Information Administration. In addition, the number of new and reactivated coal mines that began production in 2013 reached its lowest level in at least the past 10 years, the analysis says. Although 103 mines were added that year (the most recent year for which complete data are available), 271 mines were idled or closed, amounting to a 14-percent decline in the total number of productive coal mines compared to the previous year. The 2013 total was 397 fewer coal mines than in 2008, when U.S. coal production peaked. The declining number of new mines reflects reduced investment in the coal industry, strong competition from natural gas, stagnant electricity demand, a weak coal export market, and regulatory and permitting challenges, the EIA says.