The Gowanus Canal bisects the communities of Carroll Gardens, Gowanus, Park Slope, and Redhook, and extends 1.8-miles from to the Gowanus Bay Channel in the New York Harbor. Five east-west movable-bridges cross the canal starting with Union Street, Carroll Street, Third Street, 9th Street and Hamilton Avenue. The Gowanus Expressway (Interstate 278) and the IND Culver Line of the New York City Subway, an above ground section of the original Independent Subway Systems, pass overhead.
The oldest bridge that crosses the canal is the Carroll Street Bridge that was built in 1887 and is one of the few remaining examples of retractable bridges in the U.S. The Ninth Street Bridge opened in 1903, and two more bridges appeared in 1905: the Union Street Bridge (rehabilitated 1962) and the Third Street Bridge (rehabilitated 1954). These bridges were originally built as bascule-type of draw bridges. The Ninth Street Bridge was replaced with a vertical lift bridge in 2000.
The IND Culver Line Viaduct, the 91-foot-tall cement railroad bridge that crosses the canal, was built for the Smith and Ninth Street and 4th Avenue subway stations. It is the highest bridge in the subway system, due to now-antiquated navigation rules for tall-mast shipping in the Gowanus Creek under the stations. It wasn’t until the construction of the Gowanus Expressway (I-278) in the early 1940s that the last two bridges over the canal were built. The Expressway spans over the canal and the Hamilton Avenue Bridge, the first canal crossing north of the Gowanus Bay. It was opened to traffic on August 27, 1942, and consists of two pair of bascule spans, each carrying four lanes of one-way traffic (one northbound and one southbound) and a pedestrian sidewalk.