The stunning drop in oil prices is a short-term blessing that could become a long-term curse if it erases America's urgency to use alternative energy sources.

Since July, oil prices have fallen by about 70 percent. Nationally, gas is selling for an average $1.69 a gallon, down from $4.11 a gallon five months ago. You can find gas below $1.50 in South Jersey. And there's talk of $1-a-gallon gas by next year.

With plummeting stock prices, declining home values, higher food prices, and more and more layoffs, the lower prices at the pump have been the silver lining in the recession. But if the dip in oil prices derails efforts to find alternative energy solutions, it will further prolong a dependence on foreign oil, which is a national security threat.

Cheap gas also could slow efforts by U.S. automakers to develop more fuel-efficient cars. That's another reason to take advantage of the low prices at the pump now to raise the federal gasoline tax. Yeah, consumers will balk. But higher gas taxes make sense for several reasons:

The revenue could be used for needed infrastructure projects. At the same time, the steeper cost for gasoline will maintain the push to develop more fuel-efficient cars, increase conservation, and reduce the country's reliance on foreign oil.

Increased conservation will help reduce carbon emissions, which threaten the environment.

The impact of higher gas prices on commuters would help limit sprawl, reduce traffic, and bolster the positive trend toward increased use of mass transit.

Even with lower gas prices, Americans continue to ride buses, subways and commuter railroads at a record pace. Nationwide, mass transit ridership increased 6.5 percent in the third quarter compared with the same period last year, and commuter-rail ridership from Philadelphia to Harrisburg was up 21 percent. Locally, SEPTA and PATCO also are seeing more riders.

That's because Americans are driving less. In October, vehicle miles traveled were down 3.5 percent nationally from a year earlier. It was the 12th straight month of declines. In September, Americans drove 11 billion fewer miles, or 4.4 percent less, than the year before.

Unfortunately, federal, state and local budget cuts have already forced some transit agencies to raise fares. That's a trip in the wrong direction that could chase riders away. Growing mass-transit ridership is good public policy. Budget writers need to keep that in mind.

Today's low gas prices are unlikely to remain once the recession ends and demand picks up. Indeed, a recent survey of 52 energy executives found that more than half thought the United States could run out of reasonably priced oil within the next quarter-century. All the more reason to invest in strategies that increase fuel efficiency, bolster mass transit, and help develop more renewable energy sources.