Interstate 25, North of Wheatland, is open both directions after a Tuesday morning tanker crash closed the highway.
Wyoming Highway Patrol spokesman Stephen Townsend says the accident happened shortly after three a.m.
Townsend says the tanker truck, carrying 800 gallons of crude oil, spilled when it crashed, ending up on its side.
The driver, who was not hurt, swerved to miss a deer.
The main north-south route through the state were closed in both directions for at least five hours as crews cleaned up the oil.