Zenas King (May 1, 1818 – 1892) was an American bridge builder. He started his career in 1858 and moved from Cincinnati to Cleveland, Ohio, around 1861. He established a bridge-building works on Wason Street in Cleveland in 1865. King founded the King Iron Bridge and Manufacturing Company in 1871. As early as 1878, it was manufacturing many types of truss, combination, and wooden bridges, and by the 1880s it was the largest highway bridge works in the United States. Production moved from Wason Street to larger facilities on Ruskin Avenue in 1888. The company changed its name to the King Bridge Company after his death. Early life King was born on May 1, 1818, in Kingston, Vermont, and his father was a farmer. After his father moved to St. Lawrence County, New York, to a new farm, King lived at that farm until he was 21 years old. He moved to Milan, Ohio, to take contracts for erecting buildings. In 1848, he and C. H. Buck worked in mercantile business for eight years. With his health deteriorating, King became a traveling agent for a Cincinnati agricultural machinery house. He later became an agent for the Moseley Iron Bridge and Roof Company and started studying bridges. Career King was an assistant of Thomas William Moseley, who patented the design of a wrought iron tubular bowstring bridge in 1857. King improved upon Moseley's efforts by emphasizing distribution and marketing across the United States. Despite not being trained as an engineer, King knew about the sale and manufacture of boiler plating for farm machinery. He used this knowledge and with the help of a metalworker named Peter Frees, the two of them sent in a patent for a way to improve the bowstring arch form. Their innovation was at first considered to not be groundbreaking enough to receive a patent, but King appealed directly to the commissioner of patents about making a few adjustments to the design which was a success. His bridge types were originally used in Ohio, later being built in almost every U.S. state. Other bridge building companies took notice of his business and entered into the bowstring bridge market; the number of these bridges expanded significantly after the Civil War. In 1864, King and Frees split up and King continued to build bridges. In 1871, King founded King Iron Bridge and Manufacturing Company. King built a factory in