Fort Boise was originally built by the British Hudson's Bay Company to compete with the American Fort Hall, near present day Pocatello, for fur. But by the 1840s, the fur trade was declining, and the emigrants were increasing. The fort served the wagon trains throughout the 40s but floods plagued the area—and by 1855 Ft. Boise was gone.

Eight years later a new Ft. Boise was built 50 miles to the east—and the city of Boise grew up alongside. Except for the start and finish, Boise was the largest city on the Oregon Trail. Over a century later, it still is.

By the time the emigrants struck west from Ft. Boise, it was mid-September. There was always a danger of getting caught in the deep snow going over the Blue Mountains of Eastern Oregon. If they made it over the Blues, the Sierras presented a formidable crossing in autumn. There was always a danger of being stranded in the mountains, a fate that happened to the Donner Party, who, to ward off starvation, resorted to cannibalism. That fear was on the mind of nearly everyone as they hurried through this Fort Boise region with over 400 miles still to travel.