Lewis and Clark traversed part of the route that would one day become U.S. Highway 12 during their 1804-06 Corps of Discovery mission to the Pacific Ocean.

So did the Nez Perce Indians during the tribe's epic 1877 flight on horseback from the U.S. Army.

Now two of the nation's largest oil companies want to drive mammoth truckloads of refinery equipment along the narrow ribbon of spectacular mountain road that borders national forests, wild and scenic rivers, historic sites and campgrounds. Local residents are not pleased.

"This is something that weighs 600,000 pounds, is two-thirds the length of a football field and 30 feet high," said Linwood Laughy, who has sued the Idaho Department of Transportation to stop the mega-loads. "I don't think it belongs on the highway."

Laughy prevailed in Idaho District Court and the Idaho Supreme Court will hear arguments Oct. 1 on an appeal by ConocoPhillips. If the company wins, it likely faces a similar court fight in neighboring Montana.

That a mundane road permit application would ignite into an uproar is unusual, pitting the oil companies against a handful of residents who live along the forest shadowed highway in Idaho and Montana.

U.S. 12 runs from Aberdeen, Wash., to Detroit. But the oil companies want to cross a stretch of it that is designated as either the Northwest Passage Scenic Byway, the Lewis and Clark National Historic Trail or the Nez Perce National Historic Trail. For 100 miles it tightly borders the Lochsa and Clearwater, both designated Wild and Scenic rivers.

"A big share of my business is tourism," said Cynthia Statler, a Lakota Indian who owns a gift shop in Orofino. "This is terrible for tourism."

The dispute involves two different projects. ConocoPhillips is seeking an oversized load permit to ship four coke drums — huge pressure vessels that refineries use to make gasoline and coke — to its operations in Billings, Mont., and that case is currently in court.

But locals are much more worried about efforts by ExxonMobil Canada and some subsidiaries to get permission to ship 207 mega-loads of refinery equipment through the two states to the controversial Kearl Oil Sands in Alberta, Canada. Those loads will take a year and force temporary closures of U.S. 12 five nights a week.

All of the equipment is built in South Korea and would be barged up the Columbia and Snake rivers to Lewiston, Idaho, the most inland seaport on the West Coast. From there, it would be loaded on special transports so wide they cover both lanes of the shoulderless road.

Each truck would move only at night but take nine days to cross Idaho and Montana. And, yes, the rigs would be 3 stories tall, more than 200 feet long, and 8 times heavier than a loaded semi-truck.

Because the trucks will require a rolling road block, stopping traffic up to 15 minutes as they pass, locals fear that fire and ambulance services will be disrupted.

Residents are also concerned that U.S. 12 is the only east-west road across Idaho for a 300-mile stretch from Interstate 90 in the north to near Sun Valley in the south. A truck accident that closed the highway would force detours of hundreds of miles, Laughy said.

Since utility lines will be moved and bridges strengthened, they think the road could become a permanent route for high and wide loads.

But Pius Rolheiser, a spokesman for Imperial Oil in Calgary, Alberta, an affiliate of ExxonMobil, said the company only intends to run the 207 mega-loads for which it has requested a permit.

He said using railroads or interstate highways is not an option because the loads could not fit in most tunnels or beneath overpasses.

The equipment will be assembled once it reaches its Canadian destination to become the processor where oil is extracted from sand, Rolheiser said. Some of the opposition to the transport is from people who oppose the oil sands project for other reasons. Environmental groups have called the Canadian oil sands "the most destructive project on earth."

Meanwhile, ConocoPhillips had shipped the four drums to the Port of Lewiston in May, and in August received a special permit from the Idaho Department of Transportation to move them to Billings.

The company was caught off-guard when Laughy, his wife and neighbor Peter Grub sued the agency in state court, saying it failed to consider the convenience and safety of local residents. After a hearing, Idaho Second District Judge John Bradbury revoked the permits. The four drums are still sitting at the port.

In its appeal, ConocoPhillips lawyers evoked the spirit of Lewis and Clark, saying one goal of the famous expedition was to aid early American commerce. Using the road to assist modern day commerce is consistent with those historic principles, according to the company.

Montana officials are still studying permit applications, although government officials are already performing some $40 million worth of work to move utility lines and strengthen roads. The city of Missoula, through which the loads would pass, opposes the shipments. In a largely symbolic gesture, the city council doubled the permit fees for oversized loads to $200.

In Montana, the Canada-bound trucks would head down Highway 200 along the Big Blackfoot River — of Norman Maclean's literary "A River Runs Through It" fame — before driving through grizzly bear habitat to reach Canada.

"If one of those wide loads falls into the Lochsa or Blackfoot river, it doesn't look like they would be able to get it out," said Michael Garrity of the Alliance for the Wild Rockies, which opposes the shipments. "I don't think they looked at all the actual problems."

Neither does U.S. Rep. Peter DeFazio, D-Oregon, who says the plan essentially has U.S. taxpayers subsidizing Canadian oil production and South Korean refinery equipment by paying for wear and tear on highways.

"I am opposed to subsidizing ExxonMobil oil sands mining in Canada with taxpayer dollars," DeFazio wrote to U.S. Secretary of Transportation Ray LaHood .

One clear winner would be the Port of Lewiston, which is 365 miles from the Pacific Ocean. Director David Doeringsfeld called the shipments a significant business opportunity that could lead to increased manufacturing in the Lewiston area.

That may be why Republican Gov. Butch Otter and the Idaho transportation department have backed the shipments so enthusiastically.

"This delay costs money and jobs for people in northern Idaho, and in this economy every opportunity is critical to our economic recovery," said Otter press secretary Jon Hanian.

But Laughy isn't buying it.

"There's nothing in it for Idaho," he said. "Basically, we take the risks and they take the profits."

Opponents of the shipments: www.fightinggoliath.org