Wyoming, like New Mexico, was awfully stagnant this decade, at least compared to most other Western states. Its population is projected to have only increased by 3.3% (from 563,626 to a projected 582,328)!
Why was that?
2.7%, actually (578,759). It lost population in the last 1-2 years.
Probably because despite the oodles of cheap land and tremendous potential for developing a strong renewables market with solar and wind farms, Wyoming has spent the past several decades putting all its eggs in the coal basket. For at least 30 years, Wyoming has been dramatically ramping up coal production at massive surface mines, particularly in the northeast quadrant of the state, to the point that it now dominates the coal market in America. As the coal industry now sings it final swan song, the state finds itself with a needlessly underdeveloped economy. About the only other sectors propping the state up are ranching, which isn't particularly effective at driving population growth, and tourism, which is entirely confined to Yellowstone and Jackson Hole.