U.S. crude production hit a 43-year high last year but has been declining ever since, according to the U.S. Energy Information Administration.
The EIA said U.S. field production of crude oil grew for the seventh straight year in 2015, reaching 9.42 million barrels per day.
That level marked the highest crude oil production level since 1972, based on final production numbers in EIA’s Petroleum Supply Annual.
Texas, the U.S. Gulf of Mexico and North Dakota saw the largest production gains last year.
Those three regions accounted for 77 percent of the U.S. total increase, the EIA said.
While annual production grew in 2015, monthly U.S. crude oil production has been declining since April 2015.
Production fell to 8.74 million bpd in August 2016 after two years of low oil prices slowed down development activity.
States or areas with the highest production volumes also saw the largest gains in 2015.
Texas is still the largest crude producing state, pumping 3.46 million bpd in 2015.
That level was the highest production level in Texas since at least 1981, when the EIA began publishing its state-level production series.
Production in Texas jumped by 289,000 bpd in 2015, the largest increase of any state.
The Federal offshore region of the Gulf of Mexico was the second largest producer in 2015 and also booked the second largest production jump of any area or state.
Production in the Gulf of Mexico grew by 118,000 bpd to hit 1.52 million bpd in 2015.
That production level marked the highest production level in the area since 2010.
North Dakota took the third spot as the largest producer in the United States and also recorded the third largest production spike in 2015.
North Dakota saw production climb by 96,000 bpd to reach 1.18 million bpd last year, the highest production level on record for the state.
California production continued to decline to an average 550,000 bpd last year, down from a high of 1.08 million bpd in 1985.
Crude oil production in Alaska fell for the thirteenth straight year to 480,000 bpd in 2015, with most of production coming for the North Slope, according to the EIA.