Coal Production & Mining
Wyoming produced 239 million short tons (MST) of coal in 2021, a 9 percent increase from 2020. Coal production has been on an overall decline since the late 2000s, a trend that can be attributed to the widespread retirement of coal-fired power plants, sustained low natural gas prices, and increasing competition from renewables.
Despite decreasing production, Wyoming remains the most prolific coal-producing state in the nation. Annually, Wyoming’s coal mines account for almost 40 percent of U.S. coal production. Wyoming’s large surface coal mines are also the most efficient in the nation, with an average recovery factor of 92 percent (DOE-EIA, 2015). Statewide, the average production of coal per employee is 23 short tons per hour. This is the highest productivity in the nation and more than double the productivity of the next top coal-producing state.
Between 1865 and January 1, 2022, more than 12.6 billion short tons of coal had been mined in Wyoming, most of it in the last 30 years. The highest coal production year for Wyoming was 2008 when 466.3 MST was mined.
Coal mines operate in Campbell, Lincoln, and Sweetwater counties. The majority of Wyoming’s coal, however, is produced from the 11 mines in Campbell County. In late 2021, the Bridger mine, which was the only underground coal mine in the state, closed after extracting all of its leased coal.
The table below shows Wyoming coal production in short tons, by county and by method of mining for 2021 (Source: Annual Report of the State Inspector of Mines of Wyoming).
Coal Distribution
Nearly all of the coal mined in Wyoming is shipped via rail to destinations across Wyoming and 26 other states. The top consumers of Wyoming coal are coal-fired power plants in Texas, Missouri, Wyoming, and Illinois. While the majority of the coal is used to generate electricity at power plants, it is also delivered to industrial plants and commercial facilities.
Powder River Basin Mining
In the Powder River Basin coal field—the most prolific in the world—coal is mined from two major coal seams, the Anderson and Canyon coals. This coal occurs in the Paleocene-age (65–55 million years ago) Tongue River Member of the Fort Union Formation. The mineable subbituminous coal seams in the Fort Union Formation are 60–80 feet thick, with a moisture content between 20 and 30 percent, and contain less than 6 percent ash and 0.5 percent sulfur. Powder River Basin (PRB) coal also includes beds in the Eocene-age Wasatch Formation, where exploration drilling has encountered coal seams greater than 200 feet thick.
Coal is mined in the PRB at a rate of 12 tons per second, filling between 50 to 70 coal trains per day. Seven of the nation’s 10 largest coal mines operate in the Wyoming part of the PRB. The largest coal mine is Peabody Energy's North Antelope Rochelle Complex, which produced more than 62 million tons in 2021.
Rapid growth in Wyoming's coal industry during the latter part of the 1970s resulted from the development of large-scale open-pit surface mines in the PRB. Development of the abundant coal resources in the PRB was driven by amendments to the Clean Air Act of 1974 and the subsequent energy crisis. The continuous growth of coal production in Wyoming resulted from a growing national demand for low-cost, low-sulfur steam-coal, as well as technological advances in engineering and mining practice, large-scale development of mining and rail infrastructure, and the great abundance of thick, mineable coal resources in the PRB.
The PRB also has more than 1,500 square miles of reddish clinker rock that is mined for use as aggregate in construction and decorative applications. Clinker beds, which can be up to 180 feet thick, are layers of sedimentary rock that have been altered by the burning of an adjacent coal seam. Outcrops of coal exposed at the surface can be ignited by lightning strikes or brush fires. These fires can spread across a coal bed and into the subsurface, burning for hundreds of years. As they burn, they heat up the surrounding rock, altering it and in some cases melting the rock. Recent age dating suggests that these clinker beds formed between 1.1 million to 10,000 years ago (Heffern and others, 2007).
Excel file containing Wyoming's quarterly coal mine production and employment, according to Mine Safety and Health Administration (Last update: Third quarter, 2024).
Contact:
Kelsey Kehoe, kelsey.kehoe@wyo.gov