What is known as the Oregon Trail is one way the Fur Trappers used. The Oregon Trail was on the South side of the Platte River. Through Nebraska and Wyoming to the Sweetwater. The Mormon Trail stayed on the North side. The early days of the Fur Trade the Missouri River was the main route into what is now Montana. Another route was to follow the South Platte to what is now the area of Ft. Collins, CO. They then went North into the Laramie Valley, essentially what is now known as the Overland Trail. In western Wyoming the Oregon Trail went down to Ft. Bridger, but there was also the Lander cutoff that went through the Wyoming Range.