When engineers rebuilding a beach near Lewes, Delaware, in 2004 began finding bits of Colonial-era pottery mixed in with the sand, archaeologists quickly realized they had found a historic shipwreck. Soon, researchers were carefully excavating the wreck, which historians believe is the British vessel Severn, sunk in a storm in 1774.

They've recovered more than 45,000 "world-class artifacts … nowhere else on the continent do we have this kind of stuff from this period," says David Clarke, the state archaeologist for the Delaware Department of Transportation (DelDOT), which received money for the dig from a special pot created by federal highway-building legislation. That pot, officially known as the Transportation Enhancements (TE) program, "has pumped a lot of money into our field," he says.

More than $51 million, to be exact. But Clarke and other archaeologists are now watching anxiously as Congress debates whether to renew the enhancements program. Many lawmakers are calling for modifying the program, which has funneled funds to some 200 archaeology projects since 1992, and some want to kill it, calling it wasteful and unnecessary....