I don't recall exactly but I think it was somewhere around 1943. There is a plaque at the base of "Bomber Muntain" in the Big Horn Mountain Range in Wyoming. You would never know by the photos but the wreckage is located at I believe 13,000. I have other photos taken looking down on Lake Florence and based on those you can tell it is VERY high up.
I just found this link.
Bomber Mountain
Rick