At the same time, Americans are pumping significantly less gasoline. While that is partly a result of the recession and higher gasoline prices, people are also driving fewer miles and replacing older cars with more fuel-efficient vehicles at a greater clip, federal data show.

Taken together, the increasing production and declining consumption have unexpectedly brought the United States markedly closer to a goal that has tantalized presidents since Richard Nixon: independence from foreign energy sources, a milestone that could reconfigure American foreign policy, the economy and more. In 2011, the country imported just 45 percent of the liquid fuels it used, down from a record high of 60 percent in 2005.

"There is no question that many national security policy makers will believe they have much more flexibility and will think about the world differently if the United States is importing a lot less oil," said Michael A. Levi, an energy and environmental senior fellow at the Council on Foreign Relations. "For decades, consumption rose, production fell and imports increased, and now every one of those trends is going the other way."

How the country made this turnabout is a story of industry-friendly policies started by President Bush and largely continued by President Obama -- many over the objections of environmental advocates -- as well as technological advances that have allowed the extraction of oil and gas once considered too difficult and too expensive to reach. But mainly it is a story of the complex economics of energy, which sometimes seems to operate by its own rules of supply and demand.