The Casper Tribune has an article on the highest structures in Wyoming. Most believe 12-story McIntyre Hall at the University of Wyoming is the tallest in the state. However the Wyoming Almanac notes the Jim Bridger Power Plant in Sweetwater County is 24 stories high — although it’s a smoke stack. Ironically, though the tallest manmade structure is a 700-foot tower near Gillette owned by the Coast Guard nominally aimed at helping navigation in the Great Lakes! The tower part of the LORAN-C network is based on 1950’s military technology for providing precise navigation radio signals (LORAN = LOng RAnge Navigation) . The towers are be retrofitted so they will compliment and provide an emergency land-based backup to GPS.
Wikipedia reference to LORAN
Wikipedia List of Tallest Structures By State