The United States has significantly ramped up its oil production in recent years, so much so that the country is now producing more than it imports—which hasn’t happened in 16 years.

In the month of May, petroleum operations in the U.S. surpassed the total amount of oil being imported. The nation last experienced this turnaround in January 1997—back when the average price of gasoline was $1.29 per gallon, according to data from the U.S. Energy Information Administration.

The switch that occurred four months ago was the culmination of several years of imports trending downwards, while American oil firms expanded drilling in several states.

The volume of imports first began to dip in 2006, after the amount of foreign petroleum brought into the U.S. peaked at slightly more than five billion barrels in 2005. Imports kept shrinking overall during the next seven years, falling by 22.5%, until the country was receiving about 3.8 billion barrels from overseas.

Meanwhile, domestic oil production began to increase in 2009, which was the first time that had occurred since 1992. The jump was nearly 7% from 2008 to 2009, to 1.95 billion barrels, and by 2012, American drilling yielded another boost of 21.7%, to 2.38 billion barrels.

Last year alone, U.S. production of petroleum grew 15.3%, which was striking compared to the global average of 2.2%.

Much of the increase in domestic production has come from just four states: Texas, North Dakota, Oklahoma and New Mexico.

American output is so strong that if it continues on this pace, the U.S. will pass Saudi Arabia as the world’s largest petroleum producer before 2020, according to a forecast by the International Energy Agency.

Part of the U.S. turnaround has to do with decreased consumption. In 2012, domestic petroleum consumption fell 1.6% to 18.6 million barrels a day, the smallest since 1996. Much of this decline has to do with cars being more fuel-efficient and with Americans driving less.

-Noel Brinkerhoff

To Learn More:

The Reemergence of the United States as a Global Petroleum Producer (by Edwin Bennion and David Mead, Bureau of Labor Statistics)

Weekly U.S. Regular All Formulations Retail Gasoline Prices (U.S. Energy Information Administration)

Largest Oil Refinery in U.S. is Owned by Saudi Royal Family and Anglo-Dutch (by Noel Brinkerhoff, AllGov)