The Chicago River isn’t just water-it’s a moving artery of the city, and the bridges that cross it are engineering stories written in steel and concrete. Few places in the world have as many movable bridges as Chicago, and none have turned the simple act of opening a bridge into an art form. The bascule bridges here aren’t just functional; they’re iconic. They’ve lifted for freighters, ferried streetcars, and let sunlight dance on the river below. And they’ve done it all for over a century.
Why Chicago Needs Movable Bridges
Chicago’s river flows backward-literally. In 1900, engineers reversed its course to keep sewage from polluting Lake Michigan, the city’s drinking source. But that meant the river had to stay open for boats. Ships carrying grain, coal, and lumber needed to get from the Great Lakes to the Mississippi River system. So bridges had to move. Fixed bridges? They’d block the way. That’s where the bascule came in.
A bascule bridge is like a seesaw. One side goes up, the other down, balancing the weight. It’s simple, strong, and efficient. Chicago didn’t invent it, but it perfected it. By the 1920s, the city had more movable bridges than any other city on Earth. Today, 48 of them still operate, and most are bascule designs.
The Michigan Avenue Bridge: A Crown Jewel
If you’ve seen postcards of Chicago, you’ve seen the Michigan Avenue Bridge. Officially called the Michigan Avenue Bridge a double-leaf bascule bridge completed in 1920 that carries Michigan Avenue over the Chicago River and is known for its ornate Beaux-Arts design and massive stone towers, it’s the most photographed bridge in the city. Its twin towers rise 148 feet, decorated with sculptures of sea creatures and mythological figures. The bridge’s bascule leaves each weigh 1,000 tons. When they lift, they rise at a 45-degree angle in under a minute.
Before this bridge, crossing the river meant a long detour. The 1920 opening changed everything. Suddenly, people could walk from the Loop to the Gold Coast without leaving the city. The bridge also carried streetcars until 1965. Today, it handles over 100,000 vehicles a day-and still opens 70 times a year for tall ships and barges.
The Innovation Behind the Lift
Chicago’s bascule bridges didn’t just happen. They were built by engineers who refused to accept the status quo. In 1902, Joseph B. Strauss-later the designer of the Golden Gate Bridge-built the first modern bascule in Chicago: the DuSable Bridge originally known as the Michigan Avenue Bridge, this double-leaf bascule bridge was completed in 1920 and is one of the largest of its kind in the world, featuring intricate architectural detailing (now called the DuSable Bridge). It used a counterweight system that balanced the lifting span. No motors. No hydraulics. Just physics.
By 1919, the city had switched to electric motors. Each bridge now has two 250-horsepower motors. They can lift a 1,000-ton leaf in 45 seconds. The bridge opens on a schedule, but emergency openings happen too. If a tall ship is coming, the city halts traffic. No exceptions. Even ambulances wait.
Chicago’s bascule bridges use a unique double-leaf design. Most cities use single leaves. Chicago’s two leaves meet in the middle. It’s more complex, but it lets ships pass through a wider channel. That’s why the river never became a bottleneck.
The Other Bridges That Made History
The Michigan Avenue Bridge isn’t alone. The Wabash Avenue Bridge a single-leaf bascule bridge built in 1928 that carries vehicular traffic over the Chicago River and is notable for its Art Deco design and steel truss structure opened in 1928. Its Art Deco railings and lanterns still glow at night. Then there’s the Kinzie Street Bridge a double-leaf bascule bridge built in 1908 that connects the Near North Side to the Loop and is one of the oldest operating bascule bridges in Chicago, built in 1908. It’s one of the oldest still in use. And the Columbus Drive Bridge a single-leaf bascule bridge completed in 1932 that carries Columbus Drive over the river and is known for its efficient mechanical design and minimal ornamentation, built in 1932, was the first to use a fully electric drive system without backup steam engines.
Each one has its own quirks. The LaSalle Street Bridge a double-leaf bascule bridge built in 1902 that carries vehicular traffic over the river and was one of the first to use counterweights for balance has a hand-cranked emergency system still kept in working order. Workers test it once a year. The Sangamon Street Bridge a single-leaf bascule bridge built in 1929 that connects the Near West Side to the Loop and features a distinctive steel truss and mechanical room has a small control room built into its tower, with original dials and levers from the 1930s.
How Often Do They Open?
Chicago’s bridges open about 1,500 times a year. That’s more than four times a day, on average. Most openings happen between April and October. The busiest months are June and July, when lake freighters and tourist boats flood the river.
The city keeps a public schedule. You can check it online. But if you’re standing on the riverwalk, you’ll know when a bridge is about to lift. The lights flash red. The horns blow. Traffic stops. And then, slowly, the massive steel leaves rise. It’s not just a mechanical act-it’s a performance. Locals pause. Tourists snap photos. Kids point.
The Legacy of Chicago’s Bascule Bridges
These bridges aren’t relics. They’re alive. They’ve survived wars, economic crashes, and decades of neglect. In the 1970s, the city almost tore them down. Too expensive, they said. Too outdated. But preservationists fought back. They showed that these bridges weren’t just infrastructure-they were part of Chicago’s soul.
Today, the city spends $20 million a year just on maintenance. Bearings are greased. Gears are replaced. Concrete is patched. Every bridge has a digital twin now, a 3D model that predicts wear and tear. Sensors monitor stress. Weather. Water levels. Even the vibration from passing trucks.
And they still open. Not because they have to. But because Chicago refuses to let its river be silent.
What Makes Chicago’s Bridges Unique?
Other cities have movable bridges. New York has drawbridges. San Francisco has a few. But none match Chicago’s scale, density, or artistry. The city has more bascule bridges than the rest of the United States combined. It’s the only place where you can walk across a bridge that lifts for ships, then turn around and see another one doing the same thing a block away.
They’re also the only bridges in the world that are part of a city’s daily rhythm. You don’t just drive over them. You wait for them. You listen for them. You watch them. And when they rise, the whole city holds its breath.
| Bridge Name | Year Built | Leaf Type | Weight per Leaf | Annual Openings | Notable Feature |
|---|---|---|---|---|---|
| Michigan Avenue Bridge | 1920 | Double-leaf | 1,000 tons | 70 | Beaux-Arts towers, sculptures |
| DuSable Bridge | 1920 | Double-leaf | 1,000 tons | 70 | Same as Michigan Avenue Bridge (historical name) |
| Kinzie Street Bridge | 1908 | Double-leaf | 850 tons | 90 | Oldest operating bascule in Chicago |
| Wabash Avenue Bridge | 1928 | Single-leaf | 650 tons | 60 | Art Deco railings and lighting |
| LaSalle Street Bridge | 1902 | Double-leaf | 780 tons | 85 | Hand-cranked emergency system still in use |
Where to See Them in Action
If you want to witness a bridge lift, head to the riverwalk between Michigan and Wabash Avenues. The best time is late afternoon on a summer day. The sun hits the water. The boats glide in. And then-the lift. It’s quiet at first. A hum. Then the gears engage. The bridge groans. And slowly, impossibly, the steel rises.
Or visit the Chicago Architecture Center a nonprofit organization that offers tours and exhibits on Chicago's architectural heritage, including the history of the city's movable bridges. They run daily bridge operation tours. You get to stand in the control room. See the levers. Hear the operators talk about the rhythm of the river. It’s not just history. It’s living engineering.
What’s Next for Chicago’s Bridges?
The city plans to upgrade all 48 bascule bridges by 2040. New motors. Better sensors. Solar-powered lighting. But they won’t replace them. Not even close. Chicago knows these bridges aren’t just tools. They’re symbols. Of ingenuity. Of resilience. Of a city that refused to choose between progress and beauty.
They’ll keep lifting. For ships. For history. For the sound of steel meeting sky.
Why does Chicago have so many movable bridges?
Chicago has so many movable bridges because the Chicago River is a major commercial waterway that connects the Great Lakes to the Mississippi River system. Fixed bridges would block large ships from passing through. Bascule bridges lift to let tall vessels through while still allowing roads and rail lines to cross the river. The city’s unique geography and shipping needs made movable bridges essential, and engineers developed them to an unmatched level of sophistication.
What is a bascule bridge?
A bascule bridge is a type of movable bridge that uses a counterweight to lift a section of the roadway, called a leaf, so boats can pass underneath. The name comes from the French word for seesaw. Chicago’s bridges typically use a double-leaf design, where two sections meet in the middle and lift symmetrically. This design allows for a wider navigation channel than single-leaf bridges and became the standard for major urban rivers.
How often do Chicago’s bridges open?
Chicago’s bridges open about 1,500 times a year-roughly four times a day on average. Most openings occur between April and October, when lake freighters and recreational boats are most active. The busiest bridges, like Kinzie Street and LaSalle Street, open over 80 times a year. Emergency openings for unexpected tall vessels also happen, and all openings are coordinated through the city’s bridge control center.
Are Chicago’s bascule bridges still in use today?
Yes, all 48 of Chicago’s movable bridges are still in active use. The oldest, LaSalle Street Bridge, opened in 1902 and still operates daily. The city invests $20 million annually in maintenance, including gear replacements, concrete repairs, and modern sensor installations. Each bridge has digital monitoring systems that predict wear and schedule repairs before failures occur. They remain vital for both transportation and river commerce.
Can you walk across a Chicago River bridge while it’s opening?
No. When a bridge is scheduled to open, all pedestrian and vehicle access is blocked for safety. Barriers lock down, lights flash, and horns sound. Even if you’re on the bridge, you’ll be stopped before the lift begins. The movement is too fast and too powerful-each leaf weighs hundreds of tons. The city enforces this strictly. But you can watch from the riverwalk or nearby sidewalks, where crowds often gather to see the spectacle.