The United States produced almost 6.5 million barrels of crude oil a day in September, according to the U.S. Energy Information Administration. That is the country’s highest volume in nearly 15 years.
The last time the U.S. produced that much oil was in January 1998.
U.S. production has risen by more than 900,000 barrels a day since September 2011 due to the combination of horizontal drilling and hydraulic fracturing.
Texas and North Dakota have posted the largest increases, but EIA says production in Oklahoma has grown by more than 56 percent since January 2010. The state produced 250,000 barrels of oil a day in September.
Oklahoma was one of five states spotlighted by EIA as smaller-volume producers whose output has risen over the past few years.