31-year-old Garilee Henderson has died in a one-vehicle rollover juat outside Rocky Boy's Indian Reservation.
The Montana Highway Patrol says the woman was traveling east on Upper Box Elder Road at 7:15 a.m. Thursday.
Authorities said she failed to negotiate a sweeping turn. Her sport utility vehicle left the road and rolled several times.
Highway Patrol said speed and alcohol were a factor in the crash.
The woman was thrown from the SUV and died at the scene.