BISMARCK, N.D. — The North Dakota Highway Patrol is reopening a state highway that has been closed for about three weeks because of an oil pipeline protest.

Patrol Superintendent Col. Michael Gerhart says state Highway 1806 was to reopen late Thursday afternoon. He says speeds will be reduced to 25 mph in some areas and troopers will be performing extra patrols on the road.

A several-mile stretch of the highway that runs through the Standing Rock Sioux Reservation in southern North Dakota had been closed since Aug. 17. Opponents of the $3.8 billion Dakota Access pipeline are protesting near a construction zone just north of the reservation.

Gov. Jack Dalrymple said Thursday that North Dakota National Guard members will help provide security at traffic checkpoints along the highway.