HOUSTON — The number of rigs exploring for oil and natural gas in the U.S. increased by nine this week to 440.

A year ago, 863 rigs were active. Depressed energy prices have sharply curtailed oil and gas exploration.

Houston oilfield services company Baker Hughes Inc. said Friday that 351 rigs sought oil and 88 explored for natural gas this week. One was listed as miscellaneous.

Among major oil- and gas-producing states, Texas gained three rigs, New Mexico and North Dakota, two each, and Louisiana, Oklahoma and Wyoming, one each.

Kansas declined by one rig.

Alaska, Arkansas, California, Colorado, Ohio, Pennsylvania, Utah and West Virginia were unchanged.

The U.S. rig count bottomed out in May at 404.