Does shale boom mean U.S. energy independence near?

Ever since Richard Nixon's 1973 promise to attain energy independence, successive U.S. presidents all have pledged the same goal, even as foreign supplies composed a larger and larger share of the U.S. energy mix.

Now, almost 40 years later, a measure of independence is within reach. But as this booming mountain town in northeastern Pennsylvania shows, the quest for independence involves both opportunities and trade-offs.

It may surprise Americans who've lived through many years of dependence on foreign fuels, but in less than a decade the United States could pass its 1970s peak as an oil and natural gas producer. If that happens - and many analysts think it's possible - the United States would edge past Saudi Arabia and Russia to become the world's top energy producer.

That alone wouldn't make us completely energy independent. Mexico and Canada are likely to remain stable providers of oil to supplement growing U.S. production. And other factors will help too, ranging from advances in battery technologies and alternative fuels such as ethanol to greater fuel economy in automobiles.

However, the biggest potential game changer for U.S. energy production is natural gas, which previously had been supplied largely from the Gulf of Mexico region. Just a few years ago, terminals were being built at U.S. ports in anticipation of importing natural gas; today, there's talk of exporting it.