The drilling boom is being driven by a variety of factors. New  technologies have allowed companies to tap vast new oil reserves in  places like North Dakota, Texas and, most recently, Ohio. High oil  prices are making once-unprofitable fields more tempting. And low  natural-gas prices are leading companies to shift their focus to finding  oil. Natural-gas drilling, which generally uses the same rigs but in  different places, is down 8% in the past year.
 All that drilling is helping to boost U.S. oil production. The U.S.  pumped 3.9 million barrels a day from onshore fields in March, up 5.9%  from a year earlier and the most in nearly a decade.
Rising production—along with other factors such as increased use of  alternative fuels and reduced consumption due to more fuel-efficient  cars—is helping to make the U.S. less dependent on foreign oil. U.S.  crude oil imports last week were down 11% from a year ago; on a  percentage basis, the U.S. imported less of its oil last year than any  year since 2003.
 The trend may not continue, however. Oil prices have fallen to about  $85 a barrel in recent weeks, down sharply from their highs of well over  $100 a barrel last spring. The drop won’t make companies stop drilling,  but lower prices combined with higher costs could be enough to slow the  rig count’s rapid rise.
 
