The number of rigs actively exploring for oil and natural gas in the U.S. rose by one this week to 1,931.

Houston-based oilfield services company Baker Hughes Inc. reported Friday that 1,432 rigs were exploring for oil and 495 were searching for gas. Four were listed as miscellaneous. A year ago, Baker Hughes listed 1,959 rigs.

Of the major oil- and gas-producing states, Louisiana gained four rigs, North Dakota three, Texas and West Virginia two each and Arkansas one.

New Mexico and Pennsylvania each declined by three rigs, Colorado and Wyoming dropped two apiece and Alaska and Oklahoma were down one each.

California was unchanged.

The rig count peaked at 4,530 in 1981 and bottomed out at 488 in 1999.