The sub-bituminous coal from the Drumheller mining district was mainly used for home heating, cooking and electrical generation. It was also used to power the steam locomotives of the Canadian National and Canadian Pacific Railways on the prairies. The flat-lying seams were easier to mine than those found in more mountainous areas, with lower levels of methane gas. The coal-mining era lasted from 1911 to 1984, when the Atlas No. 3 and 4 mines closed. The Atlas No. 3 Mine structures are preserved and form the basis of the National Historic Site, administered by the Atlas Mine Historical Society.