Tempe Historic Property Survey

The Mill Avenue Bridge is the oldest automobile crossing on the Salt River in the Phoenix metropolitan area, and has been in continuous use since its completion in 1931. It was the major transportation link in three transcontinental highways (U.S. Routes 60,70, and 80) and Arizona’s only north-south route, U.S. Route 89, until the freeway system was begun in the 1950s. The bridge was built to supercede an earlier highway bridge, built 1911-1913, which had become increasingly congested and was no longer able to adequately support wider and heavier vehicles. In 1928, a group of Tempe businessmen submitted a request to the Arizona Highway Commission that a new bridge be planned. The bridge was designed by the Arizona Highway Department in 1929. Ralph Hoffman, the bridge engineer for the State of Arizona, signed the contract with Lynch-Cannon Construction Company of Los Angeles, implementing Federal Project 2-B. The bridge was opened to traffic in August of 1931, but was not officially dedicated until 1933. Presiding at the ceremony was Arizona Governor B. B. Moeur, a Tempe physician.

The Mill Avenue Bridge is a ten-span poured concrete, open spandrel structure. The spans are multiple ribbed with open spandrels, each 140 ft. long, supporting a concrete roadway on beamed and webbed columns above the ribs. The ribs are designed as hingeless arches fixed at the piers. Two types of piers are used in the design and the spans are divided into groups of three, four, and three, separated by abutment piers. Abutment piers are of a typical column construction. Abutment piers are extended and carried above the roadway level in four hexagonal towers forming pedestrian rest bays with canopies. This effect is maintained with hexagonal pylons terminating the railings at each end of the bridge.

For more details see Excerpts from Newspaper Articles and Documents about the Mill Avenue Bridge

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