HOUSTON (AP) - The number of rigs actively exploring for oil and natural gas in the United States rose by 23 last week to 1,990.

Of the rigs running nationwide, 1,586 were exploring for natural gas and 395 for oil, Houston-based Baker Hughes Inc. reported Friday. Nine were listed as miscellaneous.

A year ago, the rig count stood at 1,795.

Of the major oil- and gas-producing states, Colorado gained eight rigs, Alaska five, Wyoming four, Louisiana three and North Dakota two. New Mexico lost seven rigs, Arkansas lost two and Texas lost one. California and Oklahoma 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.