The crossing of the Delaware River at Easton, Pennsylvania, provided a central link in travel from the northeastern seaboard to America's inland territories throughout the 18th and early 19th centuries. From 1806 to the mid-1890s, travelers used a landmark wooden structure built by noted bridge-builder Timothy Palmer. By the 1880s, however, Palmer's three-span covered bridge could no longer handle the demands of traffic generated by new trolley lines.
Combining aesthetics with economical design, the Northampton Street Bridge employs a cantilever design with overhead sway bracing confined to the pier elements, giving it the appearance of a small, graceful suspension bridge. Fine ornamental work and miniature turret finishings on the main verticals add to the bridge's elegant presence. Built for the Delaware Bridge Company and operated as a toll bridge, it was sold to the Delaware River Joint Bridge Commission in 1921 and has been toll-free to automobile traffic ever since.
- The Northampton Street bridge consists of a 300-foot center span and two side spans of 125 feet each. It was designed by James Madison Porter, a professor of civil engineering at nearby Lafayette College, and built by Charles Macdonald, founder and president of the Union Bridge Company and president of the American Society of Civil Engineers in 1908.
- Only two other bridges of similar design are known to exist in the United States -- the Frisco Bridge, a railroad bridge crossing the Mississippi River at Memphis, Tennessee built in 1892, and the swing span of the double-deck railroad and highway bridge crossing the Mississippi at Rock Island, Illinois built in 1893.
- Hurricane Diane caused massive flooding along the Delaware River in 1955, creating a break of about 100 feet in the central span of the Northampton Street bridge. Temporary bridges erected just north of the structure carried traffic for two years while the bridge was being repaired. In 1990, the entire bridge underwent a thorough restoration.
- Carol P. Henry, Charles L. Best, Jackson L. Durkee, "Northampton Street Bridge"; Journal of Structural Engineering, Vol. 110, No. 7, July 1984.