BISMARCK, N.D. (AP) -- The number of rigs drilling for oil in North Dakota is at the lowest level in a year and a half.
The State Department of Mineral Resources reports that just more than 180 rigs were drilling this week. Agency spokeswoman Alison Ritter says that's the lowest level since July 2011.
A record 218 rigs were drilling in western North Dakota's oil patch in late May.
Ritter says the drop in drilling is due partly to more efficient rigs and the increased costs to operate them. She says some drillers also are cutting back to stay within their 2012 budgets.