This is the Union Pacific 3985 under full power headed West out of Green River and up Peru Hill. This is amazing to watch in person, about 5,000 horsepower.
By request, here's a closer-up taken in Green River's rail yard.
By popular demand, new Rock Springs chamber site:
http://www.rockspringswyoming.net/
Chamber of commerce information and other events taking place at the time of your visit. Take in the fair or rodeo while in town this summer. Gathering of Outlaws, International Days, Flaming Gorge Days, Thursday farmer's markets, there is something every week in Rock Springs.
http://www.tourwyoming.com/
Sweetwater County tourism site has list of all activities by day, month, and type of show.
If you click the pages top links on "NOT TO MISS" you can locate the events calenda