U.S. crude oil output fell 276,000 barrels per day in July to 11.81 million barrels per day (MMbbl/d), its third monthly decline from its record high in April at 12.12 MMbbl/d, according to a U.S. Energy Information Administration monthly report released on Sept. 30.
A majority of the drop in production came as federal offshore Gulf of Mexico production slid about 332,000 bbl/d to 1.58 MMbbl/d, the data showed.
Output in North Dakota rose by 14,000 bbl/d to a record 1.41 MMbbl/d while Texas production climbed by 40,000 bbl/d, rising above 5 MMbbl/d for the first time since the agency began tracking output in 1981.
A shale boom, led by output increases in Texas and North Dakota, helped make the United States the biggest oil producer in the world, above Saudi Arabia and Russia.
However, the rate of growth has slowed this year as U.S. energy firms have reduced the number of oil rigs for a record 10th month in a row as producers follow through on plans to cut spending on new drilling this year.
Meanwhile, monthly gross natural gas production in the lower 48 U.S. states rose to a fresh record high 101.34 billion cubic feet per day (Bcf/d) in July, compared with a revised 101.19 Bcf/d in June, according to the EIA's 914 report.
In Texas, the biggest gas producing state, output increased 1.8% to a record high of 27.96 Bcf/d from 27.46 Bcf/d in June.
In Pennsylvania, the second-biggest gas-producing state, output edged higher by 1.9% to 19.09 Bcf/d from 18.73 Bcf/d in June.