Bowstring Arch Bridge

This 70-foot-long bridge is the oldest of all of the bridges in Kent Park. Its exact age is not known but it was likely constructed in the 1870s. Bowstring Bridges were so named because of the curved top chord and the bottom chord resembled the shape of an Archer’s Bow. The Bowstring design is considered the first successful all-iron truss bridge design developed in the U.S. In the 19th century, Squire Whipple, “one of the most famous engineers of his time” patented the first Bowstring Arch Truss in 1841.

This picturesque old structure originally crossed a tributary of Old Man’s Creek on Dane Road southwest of Iowa City in Liberty Township. Bowstring Arch Trusses were an inexpensive, lightweight, yet sturdy design, which made them popular. They were the state of the art from the 1840s through the 1890s.

In 1867, Zenas King, founder of the King Iron Bridge Co., of Cleveland, Ohio, patented the tubular bowstring design, which found use throughout the region east of the Rocky Mountains. This is a King Iron Bowstring Bridge. They were rendered obsolete by the increasing size and weight of agricultural equipment. Today only 19 remain in use on county roads in Iowa. Several have been preserved in parks through the country and are listed on the National Register of Historic Places.

Extensive Fabrication was necessary to restore this structure to its original appearance. It was lifted into its present location with two cranes.


Part of my "Crossing Past Time Bridges" photography series.

Location: Kent Park, Johnson County, Iowa.