It's not the wooden boards rumbling under cars as they drive over the 150-year-old Jericho Covered Bridge that make it special. Nor is it the siding and roof that form the charming enclosure.
According to Tim Andrews, an expert on covered bridges, it's the wooden beams — the trusses and arches that support the bridge — that make the structure, built the year of Abraham Lincoln's assassination, worthy of distinction and careful restoration.
"We consider the trusses to be the monuments," said Andrews, owner of Barns and Bridges of New England, the firm restoring the bridge. The decking, roof and siding are simply "wear items" designed to take abuse from weather and time, Andrews said.
Maryland once had more than 100 covered bridges, but today just six remain. Only three — including Jericho — still handle traffic. About 500 cars cross the one-lane bridge each day.
The Jericho bridge, spanning Little Gunpowder Falls along the line between Baltimore and Harford counties, is undergoing a $1.8 million restoration. The structure has seen just two major restorations since its timbers were laid across the water in 1865 to connect the mill towns of Franklinville and Jerusalem Mill.
"It's Baltimore County's only covered bridge, and it's one we'd make the extra effort to maintain," said Kevin J. Sabolcik, chief of engineering for the county's Department of Public Works.
Andrews said the Jericho bridge, which carries a single lane of traffic on Jerusalem Road over the water, is remarkable because 96 percent of the original wood remains in the trusses and arches.
Even after the painstaking restoration work, more than 90 percent of original wood will remain.
It was 1864 when residents of Baltimore and Harford counties began asking the government for a bridge over the Little Gunpowder Falls, according to records included in the bridge's listing on the Maryland Inventory of Historic Properties.
Baltimore County officials hired Thomas F. Forsyth to build the bridge in 1865 at a cost of $3,125 — with $1,000 to be paid when the abutments were in place and the balance upon completion. Harford County and Baltimore County split the construction costs.
Two covered bridges are in Cecil County: Gilpin's Falls, built in 1860 in North East, and Foxcatcher Farms in Fair Hill, built in 1860.
The other three are in Frederick County: the 1843 Utica Mills bridge near Lewistown; Loys Station in Rocky Ridge, originally built in 1848 and replaced in 1994 after an arson; and Roddy Road, built in 1856 near Thurmont.
All six are in good shape, according to Jim Smedley, an amateur historian from Nottingham who has a fascination with covered bridges. The Frederick County bridges also are undergoing repairs, and Gilpin's Falls was restored a few years ago.
Smedley, who runs a Maryland Covered Bridges website, said these structures are disappearing across America. Many have been replaced with modern steel or concrete bridges that can handle the weight of larger vehicles and trucks.
"Once they're gone, they're gone," he said of the covered bridges. "To build a new one is fine, but they don't have the significance. When somebody talks about rehabilitating a bridge, I jump for joy."
At Jericho, repairing the bridge came with the challenge of moving it — at least temporarily.
Baltimore County's contract initially called for workers to restore the span as it stood over the Little Gunpowder Falls, but Andrews' team decided that reaching sections of rotted and damaged wood required a different approach.
The bridge was lifted, and a system of wooden beams with wooden rollers was used to slide its 90-foot-long structure off the water and onto the adjacent roadway. Traffic has been diverted to other local roads.
"The original plan was to rehabilitate the structure in place," said Keith A. Duerling, an engineer with the county's Department of Public Works. "But it's a lot easier to get to everything from the ground, rather than being suspended over the water."
All that's left over the river is the bridge decking and steel support beams underneath. The beams will be cleaned and repainted, and the wooden decking, which dates to 1983, will be replaced. The siding and roof have been removed and will be replaced by contractor Kinsley Construction of Timonium.
The truss and arch repairs will take until fall, when the bridge will be rolled back into place.
Everything will be treated with insecticide and fire-retardant paint to help prevent future damage. In the past, the bridge has been tagged with graffiti and was the target of attempted arsons. The project should be completed by December.
"It's getting a whole makeover," Duerling said.
All of the work is being done with historical accuracy in mind. The bridge is listed on the National Register of Historic Places and the Baltimore County Landmarks List.
As a local landmark, the Jericho bridge is a frequent stop for visitors to the nearby Jerusalem Mill Village, which sits on the grounds of Gunpowder Falls State Park and features several buildings that date to the late 1700s.
A path takes visitors from the village to the bridge and back, notes Rick Decker, who lives nearby and is president of the volunteer group Friends of Jerusalem Mill.
Thriving commerce in the 1800s led to the bridge being built, Decker said. Jerusalem Mill founder David Lee built a village with a post office, general store and mill that ground flour and cornmeal using water power from the Little Gunpowder Falls. There was once another covered bridge over the falls about a quarter-mile away.
"It really speaks to the prosperity of the area. It became a real center of commerce for this portion of Harford County and northern Maryland," Decker said.
Others who visit the bridge aren't so keen on history but are drawn by numerous ghost stories. Some legends say resident spirits belong to Confederate soldiers — but Smedley noted that the covered bridge was built after the Civil War ended.
The Jericho bridge uses a design called Burr arch truss, designed by Pennsylvania bridge builder Theodore Burr in the early 1800s. In addition to vertical trusses that support the bridge structure, the design features one long, curved arch on either side of the span.
Andrews said engineers still debate which part of the bridge does most of the work holding it up.
"It's controversial: Are the arches carrying most of the load and the trusses supporting? Or the converse?" said Andrews, who restored the similarly designed Gilpin's Falls covered bridge in Cecil County.
The federal government, which has a grant program for historic covered bridges, is paying for most of the Jericho restoration. Baltimore County and Harford County each are kicking in 10 percent of the cost.
Covered wooden bridges such as Jericho need to be restored every 35 to 40 years.
Andrews, who is based in New Hampshire and has worked on dozens of covered bridges, said this project should ensure that the Jericho bridge lasts for years to come.
"Keep wood dry and it lasts indefinitely," he said.
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