The U.S. Geological Survey (USGS) has increased its estimate for how much oil and gas lies underneath public lands in the U.S. If exploited, these resources from onshore federal lands could power U.S. energy needs for four years in the case of oil and 12 years in the case of natural gas.

An estimated 29.4 billion barrels of oil and 391.6 trillion cubic feet of gas lie below all federal lands, as well asSource: USGS 8.4 billion barrels of natural gas liquids. USGS last estimated undiscovered oil and gas resources in these areas in 1998, when the numbers stood at 7.86 billion barrels for oil and 201.1 trillion cubic feet for gas. The increases in the resource base are attributed to recent advances energy production and now account for unconventional resources such as shale oil, tight oil and tight gas and coal-bed gas, which are routinely produced using fracking.

Half of these oil resources are found in Alaska, with 30% held in New Mexico and 5% in Nevada; North Dakota, Texas, Utah and Wyoming account for about 11% between them. The distribution of gas resources is similar, with Alaska (28%) and New Mexico (21%) still dominating. Colorado and Wyoming are the locales of about 15% each of total estimated resources, followed by Texas, Utah, Montana and Louisiana which, combined, host almost 14% of resources.