How long can the U.S. oil boom last?

In the short term, the price drop threatens profits from fracking, which is more expensive than conventional drilling. Sure enough, permit applications to drill oil and gas wells in the U.S declined almost 40 percent in November. But in the long term, the U.S. oil boom faces an even more serious constraint: Though daily production now rivals Saudi Arabia's, it's coming from underground reserves that are a small fraction of the ones in the Middle East, the National Geographic reports. That geologic reality is easy to forget in the euphoria of the boom. Output from oil fracking in the U.S. has tripled in the past three years, from about one million barrels per day in 2010 to more than three million barrels per day at the end of 2013. Total U.S. oil production has risen to more than nine million barrels a day, a level close to 1970's historic high and nearly as high as the 9.6 million barrels of daily oil production from Saudi Arabia. While the U.S. still relies on imports for about 40 percent of its petroleum, oil imports have dropped since 2005 because of improved domestic supply from oil fracking, better vehicle fuel efficiency, and depressed fuel demand as a result of the 2008 economic crash. The U.S. Department of Energy reports a growing surplus of domestic oil. Because of all these factors, oil prices that regularly reached more than $100 per barrel the past three years have dropped about 40 percent to $60 or below. On December 10 the Energy Department projected an average price of $63 per barrel for West Texas intermediate crude for all of 2015. In late November, gasoline prices in the U.S. fell to five-year lows. Details also at