HOUSTON (AP) - The number of rigs actively exploring for oil and natural gas in the United States dropped by 43 this week to 1,721.

Of the rigs running nationwide, 1,347 were exploring for natural gas and 364 for oil, Houston-based Baker Hughes Inc. reported Friday. A total of 10 were listed as miscellaneous.

A year ago, the rig count stood at 1,782.

Of the major oil- and gas-producing states, Texas lost 23 rigs, Oklahoma lost six, Colorado lost three, Arkansas lost two, and North Dakota and California each lost one. New Mexico added two and Wyoming and Louisiana each gained one. Alaska was 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.