The number of rigs exploring for oil and natural gas in the U.S. dropped 4 this week to 476, a record low and another sign of continuing price woes in the oil and gas industry. A year ago, 1,069 rigs were active. Houston-based oilfield services company Baker Hughes Inc. said Friday that 387 rigs sought oil and 89 explored for natural gas this week. Among major oil- and gas-producing states, New Mexico lost two rigs and Kansas, North Dakota, Ohio and Oklahoma each lost one. Texas gained two rigs. Alaska, Arkansas, California, Colorado, Louisiana, Pennsylvania, Utah, West Virginia and Wyoming were unchanged. The U.S. rig count peaked at 4,530 in 1981. It previously bottomed out at 488 in 1999.