Updated

The local diners, fast food shops and gas stations that cluster just off the exits of America's highways are in a fight with the Senate over a proposal to commercialize rest stops -- a move they claim would divert traffic and suck their business dry.

The proposal by Sen. Rob Portman, R-Ohio, would for the first time since the inception of the interstate highway system allow any state to open up side-of-the-highway rest stops to restaurants and gas stations.

Across the country, most of those rest stops are sleepy pockets on the side of the road -- consisting of little more than a bathroom, vending machines, parking and perhaps some brochures.

It's that way by design. Decades ago, Congress barred states from allowing commercial business directly along the interstate highways -- forcing motorists to venture off in search of food and fuel at the exits.

Exceptions, of course, persist. The mega-complexes along the New Jersey Turnpike and popular way stations along Route 95 -- like the Maryland House -- are just a few examples.

Portman's proposal could, feasibly, allow any state to go the route of the New Jersey Turnpike.

Lisa Mullings, head of the group NATSO, which represents local travel plazas and truckstops, said that would be disastrous for local businesses that for years have thrived off drivers who gas up and grab a bite at the exits.

"It would presumably put a lot of small businesses out of business," she said. "It's very shortsighted."

Portman, who is trying to get his measure voted on as an amendment to a sprawling transportation bill, would not require states to open up their rest stops to big business. Rather, the senator wants to give states the option to debate it and then commercialize the rest stops should they choose -- mainly, to help the states shore up their budgets.

A Portman aide told FoxNews.com that the existing "federal mandate" requires states to maintain the rest areas without making any money off them.

Ohio, for example, spends $50 million a year on rest-stop maintenance and improvement. That's money down the drain.

"They don't get a say in how they're used," the aide said.

But the aide said Ohio could at least break even if the state were allowed to lease off rest stops to private companies, which would then open up shop on the side of the road -- Ohio and other states could even profit off the arrangement and use that money to fix roads and bridges, the aide said.

"It would give opportunities to turn the current liability into a possible asset," the aide said. "Our amendment doesn't tell states to commercialize. It just allows them to. ... This would just send this entire conversation down to the state level."

As for businesses along the exits, they could potentially get in on the commercialized rest stops, too.

But Mullings said many of those business owners "cannot afford to abandon that investment and then go bid on a lease with the state."

NATSO, which is lobbying against the amendment along with a slew of other restaurant and gas station groups, cited stats suggesting commercialized rest stops lead to fewer businesses.

According to the group, and a coalition called the Partnership to Save Highway Communities, about 110 businesses are along the Ohio Turnpike, which has commercialized rest stops. More than 1,000 businesses, though, are along the state's Interstate 75, where rest stops are not commercialized.

NATSO projected a 46 percent decrease in gas sales and a 44 percent decrease in restaurant sales for interstate businesses if rest stops are commercialized -- that's if states decided to take that step.

State highway departments, though, are largely in favor of opening up rest stops to more business.

The American Association of State Highway and Transportation Officials has passed a resolution calling for states to have "the flexibility to commercialize Interstate rest areas." The organization noted that many states already have been forced to close down rest areas because they can't afford to maintain them on "limited resources."