Thurmont in Frederick County, Maryland — The American Northeast (Mid-Atlantic)
The Bridge that Moved
Catoctin Furnace Iron Trail
Photographed by Allen C. Browne, October 30, 2024
1. The Bridge that Moved Marker
The 1872 bridge in front of you is called a bowstring truss bridge. It originally spanned Big Pipe Creek in Detour, Maryland. Patented in 1841 by Squire Whipple, the bowstring truss bridge is composed of an arch (the bow) joined to a flat deck (the string). Between the bow and the string, diagonal beams maintain tension to support the structure. These bridges were made and shipped to creeks and streams across the country during the mid-19th century.
By the 1970s, this bridge began to have structural issues due to heavy traffic flow. It was narrowed and then transported 11 miles to its present location. This move maintained the bridges historic value while also giving it a chance to be enjoyed by a new generation. As you walk over it, imagine all of the people and vehicles that have done the same over the years.
[Captions:]
« (Left) Local newspapers reported on the unusual sight of the bridge traveling by truck to Catoctin Furnace.
» (Right) An 1841 patent illustration of the bowstring arch truss bridge. Inventor Squire Whipple patented the use of wrought iron braces to maintain tension and stabilize the arch of the structure.
Erected by Catoctin Furnace Historical Society; William G. Pomeroy Foundation; Maryland Park Service;
this page online
Topics. This historical marker is listed in these topic lists: Bridges & Viaducts • Waterways & Vessels.
Location. 39° 34.982′ N, 77° 26.065′ W. Marker is in Thurmont, Maryland, in Frederick County. It can be reached from Catoctin Furnace Road. Touch for map. Marker is at or near this postal address: 12700 Catoctin Furnace Rd, Thurmont MD 21788, United States of America. Touch for directions.
Regionally, this marker is in the Washington Metropolitan Area and in Central Maryland. It is also in the American Mid-Atlantic. Globally, it is in the North Atlantic Region, North America, the Western Hemisphere, the Western World, and the Anglosphere. Historically, it finds itself in what was once one of the original Thirteen Colonies and also the Antebellum South.
Other nearby markers. At least 8 other markers are within walking distance of this marker: Powered by Water (within shouting distance of this marker); Waste Management (within shouting distance of this marker); A Lost Pond (about 300 feet away, measured in a direct line); Hidden Labor (about 300 feet away); Ironmaster's Mansion (about 400 feet away); From Mules to Motors (about 400 feet away); Recreation For All (about 400 feet away); A Fractured Landscape (about 600 feet away). Touch for a list and map of all markers in Thurmont.
Other markers no longer nearby. Raceway and Dam (was here, next to this marker but has been replaced with another marker now near it); Bowstring Arch Bridge (was within shouting distance of this marker but has been replaced with another marker now near it); Slag Heaps (was about 300 feet away but has been replaced with another marker now near it); Ruins of the Ironmasters House
Photographed by Devry Becker Jones (CC0), May 17, 2026
2. The Bridge that Moved Marker with the bridge in the background
Photographed by Allen C. Browne, October 30, 2024
3. The Bridge that Moved Marker
Library of Congress
4. Squire Whipple
Inventor of the bowstring truss arch bridge
Photographed by Allen C. Browne, October 30, 2024
5. The Bridge that Moved
Credits. This page was last revised on May 18, 2026. It was originally submitted on November 6, 2024, by Allen C. Browne of Silver Spring, Maryland. This page has been viewed 257 times since then and 57 times this year. Photos: 1. submitted on November 6, 2024, by Allen C. Browne of Silver Spring, Maryland. 2. submitted on May 18, 2026, by Devry Becker Jones of Washington, District of Columbia. 3, 4, 5. submitted on November 6, 2024, by Allen C. Browne of Silver Spring, Maryland.
