"The South Market Street bridge is a double-leaf bascule bridge designed by the prominent consulting engineering firm of Harrington, Howard & Ash of Kansas City and New York. The bridge was built in 1927 under the auspices of the Delaware State Highway Department. It is an example of the simple trunnion bascule design that had become by the mid 1920s the most common bascule bridge because of its relative economy and ease of operation and maintenance. The bridge is one of three pre-1957 simple trunnion bascule highway bridges that remain operable in Delaware.
The bridge consists of a 208'-long double-leaf bascule span, flanked by two steel deck girder spans that carry the approaches over the counterweight pits. The movable leaves are built-up thru girders with built-up floorbeams and stringers supporting an open steel grid deck. The 38'-wide bridge has cantilevered sidewalks finished with aluminum railings placed in 1982. The approach spans are finished with concrete parapets. At opposing corners of the bascule span are operator and machinery houses constructed of tan brick with pressed metal cornices and hipped roofs behind plain parapets. The controls are located in the north operator house. Each bascule leaf is operated by an electric motor that drives shafting and primary and secondary open reduction gear sets engaging a pinion and rack mounted on the inner curved face of the concrete piers. DelDOT rehabilitated the bridge in 1982. Work included strengthening the movable girders and floorbeams; removing the old operator’s console, electrical wiring, bascule motors and brakes, and replacing them with modern components; removing metal balustrades from the bascule span and replacing them with aluminum railings; and removing original center lock bars and replacing them with a new design center lock bar system.
Historically, the crossing of the Christina River at South Market Street has been a vital link connecting Wilmington with points south. In 1808, the Wilmington Bridge Company received a charter from the General Assembly to raise a private subscription of $15,000 to build a bridge to replace a ferry. The wooden “turn bridge” or swing span was in service until 1883 when the City of Wilmington replaced it with a metal truss swing span bridge. In 1926, the Delaware State Highway Department prepared a contract to replace the metal truss swing span, which was considered too narrow and light weight for existing traffic. The grand opening of the new South Market Street bascule bridge was Armistice Day, November 11, 1927. The bridge opening festivities were held in conjunction with a pageant and speeches. The design of the South Market Street bridge was awarded to Harrington, Howard & Ash, a consulting engineer firm that specialized in movable bridges. The firm was founded in 1914 by John L. Harrington, Ernest E. Howard, and Louis R. Ash. In the late 1910s, Harrington, Howard & Ash’s business grew rapidly, and the Kansas City based firm established a branch office in New York in 1922. Head of the office was Enoch R. Needles (1888-1972), whose first large contract was to make surveys for a series of bridges over the Chesapeake & Delaware Canal. Enamored with the Delaware countryside, Needles bought a farm in New Castle County, and became a neighbor and friend of Francis duPont, the state's highway commissioner. The South Market Street Bridge was the firm’s first major contract for the Delaware State Highway Department, but not the last. The firm, which changed its name to Howard, Needles, Tammen & Bergendorff in 1941, has had a significant influence on the course of Delaware’s transportation history. They designed the Delaware Memorial Bridge (1951, 1968) and the Delaware Turnpike/I-95 (1961-1964), along with numerous other bridges, turnpikes, and interstate highways across the nation.