Central high-plains and front range    Cheyenne to Pueblo
            High-plains and front range    Cheyenne to Raton
            Rockies and high plains    Gillette to Raton
            Rockies and high plains    Rapid City to Pueblo
            Rockies and high plains    Douglas to Limon
            Rockies and high plains    Denver to Albuquerque
            Southern high plains     Las Vegas to Junction
            Southern plains     Clines Corners to San Antonio
            Southern Rockies and plains    Salt Lake City to Austin
            Rockies and central plains     Billings to Hays
            Rockies and northern plains    Miles City to Salina