Chicago is not just home to many of the world’s earliest skyscrapers, it is also a city of bridges.

Next time you cross the river along Michigan Avenue, State Street, Wells Street or Wabash Avenue, look down. You’re walking on one of five different types of movable bridges found in Chicago. There’s a total of 37 movable bridges within the city limits.

The Chicago River is a system of rivers and canals with a combined length of 156 miles that runs through the city of Chicago, including its center, the Chicago Loop. Though not especially long, the river is notable because it is one of the reasons for Chicago’s geographic importance: the related Chicago Portage is a link between the Great Lakes and the Mississippi River Basin, and ultimately the Gulf of Mexico.

Chicago River Movable Bridges

The bridges across the downtown stretch of the Chicago River, between Michigan Avenue and Orleans Street, are some of the most iconic. It’s what comes to mind when you think of Chicago bridges. Most of these bridges are more than 90 years old, except for the Dearborn Street bridge which was constructed in 1962.

The first trunnion bascule bridge in the country opened in 1902 over the north branch of the Chicago River at Cortland Street. Translated from French, “trunnion” means “pivot point” and “bascule” means “seesaw”. Also known as the “Chicago Style”, the bridge’s leaves are suspended on axles (trunnions), with massive concrete counterweights located below the bridge.

What’s especially noteworthy are the bridge-tender towers at each end which have designs that incorporate Art Deco, Beaux-Arts and Modernism styles.

One of the most well-known is the DuSable Bridge (formerly the Michigan Avenue Bridge). It is a bascule bridge that carries Michigan Avenue across the main stem of the Chicago River in downtown Chicago. The bridge was proposed in the early 20th century as part of a plan to link Chicago’s South Side and North Side parks with a grand boulevard. Construction of the bridge started in 1918, it opened to traffic in 1920, and decorative work was completed in 1928.

The bridge provides passage for vehicles and pedestrians on two levels. An example of a fixed trunnion bascule bridge (which is also known as a “Chicago style bascule bridge”), it can be raised to allow tall ships and boats to pass underneath. The bridge is included in the Michigan-Wacker Historic District and has been designated as a Chicago Landmark.

The Outer Drive Bridge was one of the most important Public Works Administration projects in Chicago – spanning over the mouth of the Chicago River it is the link between the North Side and South Side. The hulking, double-decker bascule bridge was finally completed in 1937. Some say it was the longest and widest bascule bridge in the world.

The Kinzie Street Bridge is a single-leaf bascule bridge built in 1909 that spans the Chicago River.

The Van Buren Street Bridge is a bascule bridge that spans the river. It is the sixth bridge at this location and carrying this name, and was completed in 1956. It replaced an 1895 Rolling Lift-type bascule bridge.

The Bataan-Corregidor Memorial Bridge (aka the State Street Bridge), is a double-leaf bascule span opened for river traffic.

The La Salle Street Bridge (officially the Marshall Suloway Bridge) is a single-deck double-leaf trunnion bascule bridge spanning the main stem of the Chicago River. It connects the Near North Side with the Loop area. It was constructed in 1928 at a cost of $2,500,000. The bridge was part of a scheme to widen LaSalle Street and improve access from the Loop to the north side of the river. The design of the bridge, along with those for new bridges at Madison Street, Franklin Street, and Clark Street, was approved in 1916.

At the beginning and end of each boating season, every downtown bridge is lifted, to allow people to bring their high-masted boats to and from Lake Michigan. Today the bridges only open on a predetermined schedule. In the past century, they used to open whenever a boat needed to pass, causing massive disruption to both foot and vehicular traffic.

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