The Idaho State Patrol says Chet Atkinson of Weston died in the crash on Highway 36 near Preston about 6:40 p.m. Sunday.
Troopers say he was headed east in a Dodge pickup truck when he drifted off the south side of the highway near mile marker 132.
Investigators say he apparently overcorrected before he crashed through a guard rail and rolled down an embankment.
Atkinson was not wearing a seat belt. He was ejected from the truck and died at the scene. The accident remains under investigation.