Oregon Trail emigrants faced high risks crossing the North Platte River near present Casper, Wyo. River crossings were extremely dangerous; operators of commercial ferries and bridges charged steep prices. Until bridges were built, many people and animals drowned in the swift, deep, shockingly cold water of the Platte.
Fifteen miles from Prospect Hill, Oregon Trail emigrants as they neared Independence Rock began passing shallow, sometimes dry lakes. If dry, the lake floors were encrusted with snow-white alkali—essentially baking soda—which the pioneers called saleratus. It worked well for raising bread baked over sagebrush campfires.
Poetry, shouts and song—year after year, reactions were similar when Oregon Trail emigrants managed the steep climb up Prospect Hill, also called Ryan Hill, on the road from the North Platte to Independence Rock. The sight of range after range of mountains greeted them—a sweeping view of new country.
Early Oregon Trail travelers were enchanted by clear, cold water at Willow Spring, halfway between the North Platte and Independence Rock. But after traffic boomed with the 1849 gold rush, they were more often disappointed: Pioneers had cut down trees; livestock had eaten all the grass and muddied the water.
The amazing sight of Ayres Natural Bridge, a natural limestone arch across La Prele Creek near Douglas, Wyo., inspired numerous Oregon Trail emigrants to comment in their diaries. California-bound Cephas Arms on July 4, 1849, described it as “one of the wildest scenes I ever beheld.”
About 70 miles northwest of Fort Laramie, the Oregon Trail crossed La Prele Creek, flowing north from the Laramie Range toward the North Platte River a few miles away. On a high bluff above the creek mouth the U.S. Army in 1867 would build Fort Fetterman, which became an important supply base in the wars with the Cheyenne and Lakota Sioux in the following decade.