The 419,000-gallon oil spill in the lower Mississippi River last Wednesday provides more evidence that increased domestic drilling is necessary not just to meet national energy needs, but also to better protect our environment. Yes, we know that last part sounds counterintuitive. But it actually makes lots of sense. The choice is not between drilling and no drilling; the choice is between domestic drilling and importing. Domestic drilling uses pipelines, while importing uses tankers. And tankers are responsible for a far greater volume of leaks and spills than pipelines are.

The National Academy of Sciences reported that from 1990 to 1999, for instance, the average annual spillage or seepage from pipelines and oil platforms in North America was 2.06 thousand tons. From tankers, spills alone amounted to 5.3 thousand tons, while “operational discharges” added another 220 tons of fuel into our waters (even though the total volume transported through pipelines and via tankers is roughly equal). And the worst, most notable spills of the past quarter-century have usually involved tankers — including, of course, the infamous Exxon Valdez.

Furthermore, whatever drilling seepages do occur usually occur far offshore, where damage to the immediate human environment is light. That’s what happened, for instance, with the few spills during Hurricane Katrina and Rita, none of which reached land. But most tanker accidents occur near busy ports where barges and ships are vying for wharf space and river rights of way — as in last week’s Mississippi River spill — meaning closer to land, closer to people, and also often closer to the coastlines and marshes that serve as the spawning ground and cradle for many aquatic species.

As of Friday, two days after the tanker accident, a hundred-mile stretch of the Mississippi remained closed to river traffic. That means that the burden to the nation’s commerce could be considerable.

For all those reasons, drilling platforms and pipelines are safer (not to mention more economical) than tankers. And of course the more oil we produce domestically, the less we need to import. The national security advantages are obvious. Meanwhile, the simple fact is that no matter how many “alternative” sources of energy are developed for long-term use, petroleum will continue for the foreseeable future to be the primary source of transportation fuel for these United States. That’s all the more reason to drill here, drill now, and plan to drill well into the future.