A dump truck in Uniontown is expected to start a four-hour trip to Carlisle around 6 a.m. today to transport a 10,000-pound piece of national history.

The five tons constitute a slab of the Historic National Road, which was completed around 1820 as the first highway funded by the federal government, and a metal plate supporting it. Either the mayor of Uniontown or his municipal employees will be driving the road to a private conservator in Carlisle so that it can be prepared for display at Fort Necessity and potentially for local schools and museums.

The cube-like slab, which is made of soil, crushed limestone, asphalt and pavement, will be the first piece of the National Road ever to be removed intact, said National Road Heritage Corridor Executive Director Donna Holdorf. And the piece, multilayered and about 4 feet deep, will help transportation scholars understand the history behind the road.

"The slab of stratigraphy reveals, in a small way, the complete history of the National Road," said Ryan Rowles, regional archaeologist for the state Department of Transportation. "It's a window into the history of transportation in our region."

Ms. Holdorf said that the evolution of the road can also be traced and taught to the public using the slab's layers, from the dirt and rocks used many generations ago to the concrete now.

The first leg of the Historic National Road went from Cumberland, Md., to Wheeling, W.Va., across southwest Pennsylvania. It is the site of the Whiskey Rebellion and the start of the French and Indian War.

Last August, workers on the Mon-Fayette Expressway project discovered the slab intact while excavating for a bridge near the Brownsville Drive-In. As part of an agreement with the Pennsylvania Turnpike Commission, the National Road Heritage Corridor, which aims to preserve the history of the Historic National Road, was contacted about the discovery.

Workers from Turnpike Commission contractor Golden Triangle Construction Co., of Imperial, helped to crate and transport the slab out for storage at Fort Necessity.

Starting last fall, a private conservator, Brian Howard, traveled to Fort Necessity to analyze the slab and test what solvents he needs to consolidate the land. The slab -- with what local archaeologists are calling remarkably clear delineations of road layers -- needs to be consolidated so when it is cut to form multiple display segments, the layers do not crumble or mix.

Mr. Howard has been unsuccessful at consolidating the slab while experimenting on site at Fort Necessity. The slab needs to be drier for the solvents to work more effectively.

By transporting the slab to Mr. Howard's facility in Carlisle, the conservator can change the temperature and moisture around the piece.

The process will take six to nine months, Mr. Howard said, because consolidation of such a thick artifact has rarely -- if ever -- been done before, so he needs time to determine the most effective way to conserve the piece.

"It's outside the realm of the routine," he said. "It involves both experimentation and common sense and improvising as you go."

The consolidated slab eventually will be segmented and also may be polished for display. One of the portions will exhibited at Fort Necessity, which houses the Fort Necessity-National Road Interpretive and Education Center.

Ms. Holdorf said her organization also will talk with the Smithsonian Institution to see whether it wants a display, too.

But for now, the display at Fort Necessity is the only one that will definitely be created -- unless the National Road Heritage Corridor gets more money.

Ms. Holdorf said that since the slab was discovered, her organization has raised about $11,000. The revenue will be used for gas and toll expenses for the Uniontown transport, Mr. Howard's services and the purchase of a display case for the Fort Necessity road segment.

If the organization wants to create more displays, for the Smithsonian or for local museums and schools, she estimates they need an additional $4,000 to $9,000.

The organization itself faces a budget crunch. Their annual $100,000 management grant from the state is up in the air for fiscal year 2010, as Gov. Ed Rendell and legislators continue to struggle with the budget.

But the National Road Heritage Corridor has received volunteer help over the year for the display project. For instance, Golden Triangle provided its services for free, and Uniontown will provide the truck and driver for free to move the slab to Carlisle.

A self-proclaimed history buff, Uniontown Mayor Edward Fike drove the dump truck to Fort Necessity early Thursday morning to pick up the slab to store it at a garage in his town.

He said he was glad to help: "This is history in the making."