U.S. crude oil production (including lease condensate) increased during 2014 by 1.2 million barrels per day (bbl/d) to 8.7 million bbl/d, the largest volume increase since recordkeeping began in 1900. On a percentage basis, output in 2014 increased by 16.2%, the highest growth rate since 1940. Most of the increase during 2014 came from tight oil plays in North Dakota, Texas, and New Mexico where hydraulic fracturing and horizontal drilling were used to produce oil from shale formations