On the Oregon Trail, how many people died? Or if this counts too much as trivia, about what percent died?
The Wikipedia entry for the Oregon Trail has a section on deaths which gives an upper estimate of 21,000 (by all causes) out of a total of 400,000 emigrants. So the percentage of deaths based on those figures would be about 5%. The article itself quotes a figure of 4% based on a lower estimate of the number of deaths by John Unruh. The bulk of these deaths were from disease.
Of course, the number of people travelling along the route may well have been greater since there would be people who made their living carrying and supplying the emigrants but who did not intend to settle in the west. Therefore, the death rate for all travellers on the route may have been even lower.