HOUSTON (AP) _ The number of rigs actively exploring for oil and natural gas in the United States rose by 15 this week to 1,842.

Of the rigs running nationwide, 1,473 were exploring for natural gas and 360 for oil, Houston-based Baker Hughes Inc. reported Friday. Nine were listed as miscellaneous.

A year ago, the rig count stood at 1,747.

Of the major oil- and gas-producing states, Louisiana added 10 rigs, Colorado three and Alaska one. California and Wyoming each lost two rigs, New Mexico lost one and Oklahoma and Texas 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.

Copyright 2008 The Associated Press.