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Wyoming Coal

Wyoming coal fields Wyoming has been the lead coal-producing state in the United States since 1986; in fact, the coal extracted from Wyoming’s coal mines accounts for more than 40 percent of the annual U.S. coal supply. The production of coal in Wyoming contributes between $900 million and $1.2 billion in revenue to state and local governments annually. The majority of coal produced in Wyoming is used for generating electricity, with minor amounts used in industrial applications. See the WSGS pages on Coal Production & Mining for more information on coal mining in Wyoming.

Wyoming is divided into two major coal regions, the Rocky Mountain and the Northern Great Plains provinces. These areas are further subdivided into 10 coal fields defined by the extent of coal-bearing geologic formations within sedimentary basins (see map at right).

Coal in Wyoming occurs in rock sequences deposited during the Cretaceous Period 138 million to 65 million years ago (mya), the Paleocene Epoch (65 to 55 mya), and the Eocene Epoch (55 to 43 mya). The climate at those times was mostly warm and humid, suitable for substantial growth of vegetation in freshwater swamps. Organic material that accumulated in these environments was buried and transformed into the coal of Wyoming today. See the WSGS Coal Geology page for more information.

Wyoming Coal Mining

Commercial mining of Wyoming coal began in the mid-1860s with the arrival of the Union Pacific Railroad. Between 1865 and 2017, more than 11.3 billion short tons of coal were mined in Wyoming.

Collecting coal samples

In 2017, 316 million short tons (MT) of coal were produced in Wyoming, up 6 percent from the 297 MT produced during 2016, but still low compared to the 400 MT averaged over the past two decades. Coal was produced from mines in Campbell, Sweetwater, and Lincoln counties in Wyoming. Coal production charts can be found on the WSGS Coal Production & Mining page.

Coal produced in Wyoming is generally subbituminous and moderately low-ash, and some coal resources in the Powder River Basin are considered “super-compliant” with respect to environmental requirements, at less than 0.2 percent sulfur. These qualities make Wyoming coal excellent “steam coal,” used for electricity generation at power plants throughout the United States and desirable for industrial and commercial use.

Coal mined from the Powder River Basin (PRB) is consistently the most affordable coal in the nation, due to the fact that the coal occurs in thick (45+ ft) seams that are near the surface, which can be easily mined using large machinery. This combination of factors also makes PRB coal mines the most productive in the nation.

Wyoming Coal Research

The Wyoming State Geological Survey coal team studies coal resources to determine the extent of known coal beds and coal quality. The team also interprets the history of coal deposition and evolution of the sedimentary basins where coal formed. Stratigraphic and coal quality data compiled from WSGS studies can be used for exploration in the coal and petroleum industries, for developing government regulations, and for scientific investigations.

Kelsey Kehoe (307) 766-2286 Ext. 233