Associated Press

Coal industry officials say energy production and exploration played a key role in the North Dakota counties with the top average wages last year.

Oliver County ranked first with an average annual wage of $48,931. The county is home to BNI Coal's Center Mine and Minnkota Power Cooperative's Milton R. Young Station. Job Service figures show it's ranked at the top of North Dakota wage surveys since at least 1993.

Mercer County ranked third last year with an average wage of $46,776 and McLean County was sixth with $37,107.

In second place was Slope County, in an area of oil exploration, with an average wage of $48,644.

The industry group says the statewide average wage last year was $33,086.