The Main Street Bridge in Clinton, NJ, 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. Its 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.