HOUSTON (AP) - The number of rigs actively exploring for oil and natural gas in the United States dropped by 12 this week to 1,964.

Of the rigs running nationwide, 1,529 were exploring for natural gas and 423 for oil, Houston-based Baker Hughes Inc. reported Friday. Twelve were listed as miscellaneous.

A year ago, the rig count stood at 1,760.

Of the major oil- and gas-producing states, North Dakota gained nine rigs, California gained three, and Colorado and Wyoming each gained two. Louisiana lost nine rigs, Oklahoma lost six and Texas lost five. Alaska, Arkansas and New Mexico were unchanged.

Baker Hughes has tracked rig counts since 1944. The tally peaked at 4,530 in 1981, during the height of the oil boom. The industry posted several record lows in 1999, bottoming out at 488.