It's amazing what you can accomplish with the application of leverage. Last week, after years of fruitless begging to get N.C. transportation leaders to commit to building a short Interstate 73 link, S.C. transportation leaders effectively told them: "If y'all won't help us with I-73, you can forget about that Interstate 74 link to the Grand Strand you want so badly."

The N.C. folks (we're told) gulped and said OK.

Thus was hammered out, at Friday's Carolinas transportation summit at Kingston Plantation, a highway construction deal that benefits both states. The deal boosts chances that not one but two interstate highways one day will snake their way to the Strand:

I-73 will run through the Pee Dee to the state line, near Bennettsville. The N.C. Department of Transportation will plan, design and build a short link from the state line to I-74, a few miles shy of the interstate complex near Rockingham, N.C.

I-74, which now ends in northern Brunswick County, N.C., will turn toward the state line south of Shallotte. To meet it, the S.C. Department of Transportation will plan, design and build a short link between the terminus of the Carolina Bays Parkway at S.C. 9 and the state line northwest of Little River.

The sole remaining barrier to I-73 is a big one: money. Congress has not yet committed to construction money for it - though just about everyone on the House and Senate transportation committees gives it a high priority. Much of I-74 in North Carolina, in contrast, already exists.

Some who have been following the Carolinas interstate soap opera no doubt worry that if I-74 gets completed before the dirt flies on I-73, N.C. officials might forget they promised us that I-73 link. Given their spotty track record in helping South Carolina meet transportation goals, this fear is not unreasonable.

That's why the S.C. highway people should insist that North Carolina begin building its I-73 link before it completes the I-74 link between Carolina Bays and the Brunswick County line. Leverage has the power to make good things happen only if you hang onto it until you get what you want.