Production increased by 1.2 million barrels per day to 8.7 million barrels per day. In percentage terms, that’s an increase of 16.2 percent, the highest growth rate since 1940.
Hydraulic fracturing and horizontal drilling in New Mexico, North Dakota and Texas contributed to the increase, as those methods produced oil from shale formations.
Oil production has increased every year in the United States since a period of slowdowns from 1985 to 2008.
Growth is not expected to be as strong this year, the EIA reports, though production is expected to rise in 2015 and 2016. Because the price of oil has fallen by half since the middle of 2014, production has slowed in marginal drilling areas.