NEW TOWN, N.D. (AP) – Mark Fox is officially the leader of North Dakota’s oil-rich Mandan, Hidatsa and Arikara Nation after he was sworn in Wednesday afternoon in New Town.

Fox beat Tribal Attorney Damon Williams in a general election Tuesday by a slim margin. Fox received 1,240 votes and Williams 1,094 votes.

Fox’s inauguration marks the end of the Tex Hall administration. Hall held power from 1998 to 2006 and was re-elected in 2010. He presided over the bulk of the reservation’s oil boom but his administration was criticized by Fox, Williams and others as lacking transparency and failing to deal with the problems that followed oil to the Fort Berthold Indian Reservation.

The reservation produces more than 330,000 barrels of oil a day. That’s a third of North Dakota’s total output.