America's biggest coal mines of 2013: They're not all in Wyoming

Wyoming won't lose its spot as the US' coal capital any time soon: The sparsely populated state continues to host almost every major coal mine in the country, making it the largest American coal producer by far. Other states don't even come close: The biggest coal mine outside of Wyoming last year, Freedom, barely produced one-tenth of what Wyoming's biggest mine put out, and its production couldn't even top Wyoming's seventh-biggest coal mine.

But unlike in 2012 when Wyoming was home to nine of the US' ten biggest coal mines, the Cowboy State had a bit more competition last year. North Dakota's Freedom mine has taken the spot of the US' tenth biggest coal producer, as Wyoming's Caballo slid off the top-ten chart. All production figures are in metric tonnes.

Here are the top-ten biggest US coal mines in 2013 in terms of production. The information is based on data provided by InfoMine.

The biggest mines aren't always the ones with the most workers. Here are the same mines based on staff numbers rather than production volumes.