The Quebec Bridge is a riveted steel truss structure and is 987 m (3,239 ft) long, 29 m (94 ft) wide, and 104 m (340 ft) high. Cantilever arms 177 m (580 ft) long support a 195 m (640 ft) central structure, for a total span of 549 m (1800 ft), still the longest cantilever bridge span in the world (it was the all-categories longest span in the world until the Ambassador Bridge was completed in 1929). It is the easternmost (farthest downstream) complete crossing of the Saint Lawrence.
The bridge accommodates three highway lanes (none until 1929, one until 1949, two until 1993), one rail line (two until 1949), and a pedestrian walkway (originally two); at one time it also carried a streetcar line. It has been owned by the Canadian National Railway since 1993.
The Quebec Bridge was designated a National Historic Site of Canada in 1995.