Enter Wyoming from the south, and visit the Terry Bison Ranch (Exit 2), where some 2,500 head of American bison (commonly called buffalo) are raised. Back on the road, stop at the Wyoming Travel Information Center (Exit 7) for brochures and maps.

Just north of the Union Pacific tracks is Cheyenne, Wyoming's capital and largest city (Exit 9). Stops in Cheyenne include the restored Union Pacific Depot (1887), grandiose State Capitol (also 1887), Historic Governor's Mansion (1905) and the modern Wyoming State Museum. Big Boy 4004, a gargantuan steam locomotive that hauled freight trains over the Rocky Mountains, is on view in nearby Holliday Park. These attractions are within a few blocks of each other and are either free or inexpensive to visit.

The city really rocks for 10 days in July during the annual Cheyenne Frontier Days, the nation's biggest outdoor rodeo and entertainment extravaganza. In the warm months, enjoy a narrated trolley tour, a performance by the famous Cheyenne Gunslingers or a horse drawn carriage ride

From Wheatland (Exits 78 and 80), detour to Fort Laramie National Historic Site, an important garrison along the Oregon Trail, and the nearby ruts etched into the earth by westward-bound pioneers. Return to I-25 via Guernsey. North of Glendo, I-25 parallels the North Platte River. Press on to Casper (Exits 186 or 188) for the night.