The Lowthorp Truss Bridge
The Main Street Bridge, raised in 1870, is of special significance because of its early date and unique construction. Very few of its type, made with a combination of cast and wrought iron, a method used for only about 20 years, now survive in America.
Designed by Francis C. Lowthorp and fabricated by William and Charles Cowin of Lambertville, it is based on the pony truss web system patented by Caleb Pratt in 1844. It features diagonal members in tension and simple pin joints.
This bridge has been described as "an outstanding example of the early use of cast and wrought iron in truss bridges" in Clay McEldowney's treatise "The Bridges of Clinton" (New Jersey Historical Bridge Survey, D.O.T). The bridge has also been catalogued for the Historic American Engineering Record, which is available online through the Library of Congress, and by the University of Florida Civil and Coastal Engineering Department Historic Bridges project.
The appearance differs from the original only through replacement over the years of vertical members, for which rolled steel members were substituted; the original timber plank deck was replaced with solid vertical members. The original cream paint color has been retained in each repainting. It's long service is a testament to its soundness of design, quality construction, and care of maintenance.
The bridge is also significant for its important role in carrying the former New Jersey Turnpike across the river, allowing commerce and trade to flow in and out of town to great advantage.