This bridge is both a National Historic Civil Engineering Landmark and the oldest castiron bridge in the United States. It cost nearly seven times more than a wooden bridge to construct. The federal government was renovating the National Road (also called the Cumberland Road) to turn it over to the states for maintenance. As one of the largest inland ports in the country at the time, Brownsville was a starting point for traffic along the National Road and a busy boat-building town with skilled foundry workers. The bridge was heavily used and necessary to continued progress along the road. The U.S. Army Corps of Engineers procured more than 300,000 pounds of iron from Portsmouth, Ohio, and leased a foundry and its workers to make the 250 castings required. The foundry owner, English immigrant John Snowden, and engineer Richard Delafield, a West Point graduate trained in French engineering concepts, together represented “an American amalgamation of both the contemporary British and French engineering traditions,” according to the Historic American Engineering Record survey of the bridge. Delafield was assisted by Lieutenant J. K. F. Mansfield. There were delays in the construction caused by decisions about which government body had jurisdiction, selection of the best location for the crossing, and uncooperative weather. The townspeople living on the south side of the creek won the decision about location, despite Delafield's warning that it would necessitate a sharp turn onto the covered bridge then crossing the Monongahela, and would create a traffic bottleneck, which it ultimately did. It is not a large bridge, spanning eighty feet across Dunlap's Creek, and is now almost concealed by two abutting twentieth-century buildings. A pair of sidewalks has been cantilevered from the sides since the 1920s, but the bridge remains a landmark for its material, design, and antiquity.