State governor Matt Mead said late Tuesday that the 10 billionth ton would be mined in May.

The forthcoming milestone was realized thanks to calculations from the Wyoming State Geological Survey, which is tasked with keeping tabs on coal production and geology as part of its mission.

“The WSGS’s coal geologist reviewed historical records dating back to 1865 when Wyoming was still a territory,” Mead said.

“He also looked at current production data from the Wyoming State Mine Inspector and calculated a total of 9,855,067,896 short tons of coal have been mined in the state through January 1, 2013.”

Wyoming has been the top US producer of coal since 1987, making up about 40% of the nation’s annual tonnage.

The state’s North Antelope Rochelle and Black Thunder coal mines accounted for 20% of the US coal production by tons last year. During the same period all of Wyoming’s mines produced 401Mt, equating to a value of $US4 billion.

“This is a significant achievement for our state and country,” Mead said.

“Coal mining has provided thousands of jobs in Wyoming over the past 150 years, all the while fuelling America’s economy. Coal has helped make America great because it is an affordable and reliable source of energy.”

WSGS geologist Chris Caroll said Wyoming, through its coal resources, provided nearly 176 quadrillion British thermal units of energy to the country.

“This is enough energy to power the entire nation’s electricity grids for more than eight years,” he said.

“Our estimates for recoverable reserves show we can continue to produce this valuable resource long into the future, as well as expand into other potential international and economically viable markets.”

According to state statistics, Wyoming coal has the lowest sulfur and ash sub-bituminous coal in the country, meaning no washing or preparation is required prior to shipping.