There's enough oil being produced in North Dakota to displace imports from some Middle East or Latin American countries, an official said.
Lynn Helms, director of the North Dakota Department of Mineral Resources, said data from November showed the state was now producing about 510,000 barrels of oil per day, an increase of more than 150,000 bpd compared with the previous year.
Helms said oil production in the state was increasing steadily by as much as 40,000 bpd every month since June.
"This is big news for the state and the country. A half a million barrels a day represents about 10 percent of U.S. production," he said in a statement. "That's enough oil to displace imports from Iraq or Colombia."
The U.S. Geological Survey in 2008 estimated there were 3 billion to 4.3 billion barrels of oil in the U.S. part of the Bakken formation, part of which lies in North Dakota.
Canadian energy company Enbridge last month said it planned to expand its capacity into the Berthold terminal in North Dakota by 80,000 barrels of oil per day.
That expansion will accommodate growing production from Bakken and Three Forks crude oil formations in the northern United States and southern Canada, the company said.