What’s the difference between “proven” reserves and total reserves?

Answer:

Contrary to the often repeated and vastly misleading statement that the United States holds only 2 percent of the world’s oil reserves, the United States actually has enough energy to power 65 million cars for 60 years and heat 60 million homes for 160 years.

The 2 percent figure refers only to "proven" reserves — that is, an official classification of oil "that has been discovered (and) is economically and commercially viable. Sen. Lisa Murkowski explains in a Washington Post op-ed:

"In truth, 'reserves' is just one of several categories used to quantify oil and, on its own, misrepresents America's potential. To classify a barrel as a reserve, you have to drill, prove the oil is there, and meet strict criteria established by the Securities and Exchange Commission. It's not an easy process."

This number excludes the billions of barrels of oil that's off limits due to restrictive federal policy, classified as undiscovered, technically recoverable resources (UTRR) and not counted within proven reserves. According to recent government estimates, more than 116 billion barrels of UTRR oil exists on federal lands. Access to these restricted reserves will generate American jobs, increase U.S. energy security and provide significant revenues to state and local governments.

Technological advances allow the industry to recover far more oil and natural gas than previously thought reachable. For example, the Texas oil shale formation known as Eagle Ford is one of about 20 new onshore fields that some say could collectively increase U.S. oil output by 25 percent within a decade, as reported by The New York Times.