Between 1840 and 1869, historians estimate that between 250,000 and 300,000 emigrants used the Oregon Trail. At least 30,000 emigrants died along the trail, leaving an average of 15 graves for every mile. Disease, especially cholera, accidents, and hardships took their toll, while very few were killed by Indians. Most trail-side grave sites are unknown, but road construction occasionally uncovers lonely emigrant graves. A monument nearby marks the grave of a child at the Scott Spring Oregon Trail camp site, and other graves have been found in the timbers.