Main Oregon Trail

The Main Oregon Trail entered Idaho in the far southeast corner. It crossed over the Sheep Creek Hills and followed the Bear River north to Soda Springs. The route turned northwest up the Portneuf River valley and crossed Mt. Putnam to the Snake River plain and Fort Hall. The Oregon Trail then followed the south side of the Snake River across half of the state to Three Island Crossing, where emigrants forded the Snake River and traveled along the edge of the foothills to the Boise River, which was followed downstream to the second crossing of the Snake River at Fort Boise. Those emigrants which could not cross the Snake River at Three Island were forced to follow the South Alternate Oregon Trail route which was drier and rougher than the northern route.