Police said Robert Greving, 25, was working off the roadway of the highway's southbound lanes at Warner Street in Grand Haven Township when the Bobcat-like tractor struck him at about 3:20 p.m.
The Holland man was taken by ambulance to North Ottawa Community Hospital, where he was pronounced dead, said Lt. Steve Kempker of the Ottawa County Sheriff's Department.
Greving was an employee of Dan Hoe Excavating of Holland.
Kempker said it is not known why Greving was behind the tractor when it was backing up after leveling shoulder gravel. The workers were constructing a Michigan turn, and one lane of southbound U.S. 31 was closed at the time of the accident.
Sheriff's deputies were assisted at the scene by North Ottawa paramedics and Grand Haven Township Fire/Rescue personnel.