A 27-year-old Miles City man died early Thursday near Worden at milepost 21 on Highway 312.
Benjamin Capehart was strangled by his seatbelt when he was knocked unconscious after his car rolled several times, said Assistant Coroner Chad Fehr.
He would have most likely died whether he had his seat belt on or not, Fehr said.
It is believed that alcohol was a factor in the crash, he said, because containers of alcohol were found at the scene.
The wreck occurred at about 2:20 a.m., according to Montana Highway Patrol records.
Capehart was the only person in the Ford pickup at the time of the crash. He lost control of the truck while headed westbound.
His vehicle drifted to the far right side of the road and in an effort to get his truck back into the the driving lane, he overcorrected.
The vehicle left the road on the left side, rolling multiple times.
The vehicle was on its roof when crews arrived, and he was pronounced dead at the scene.
Speed was not a factor in the crash.