Cameco operates uranium mines in North America and Kazakhstan, including McArthur River-Key Lake, the world's largest uranium producer, and Cigar Lake, the world's highest grade uranium mine, both in Saskatchewan.
In the United States, Cameco operates uranium mines in the states of Nebraska and Wyoming through its US subsidiary Cameco Resources Inc. Cameco Resources was formed in 2007 through a restructuring of two wholly owned subsidiaries, Power Resources Inc. (Wyoming) and Crow Butte Resources, Inc. (Nebraska).