The St. Charles Air Line Bridge is a Strauss Trunnion bascule bridge which spans the Chicago River in Chicago, Illinois.

Built as part of the St. Charles Air Line Railroad by the American Bridge Company in 1919, the bridge originally had a span of 260 feet (79 m). This bridge held the world record for longest bascule-type span until 1930, when it was shortened to 220 feet (67 m) during a relocation as a result of straightening the river channel. The chief design engineer of the original bridge was Leonard O. Hopkins.

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  Chicago landscape with a boat
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  St. Charles Air Line Bridge, May 17, 2022.

• The adjacent B&OCT Bascule Bridge, with more information about the history of both bridges
• List of bridges documented by the Historic American Engineering Record in Illinois

• "Counterweight Repair of Historic St. Charles Air Line Bridge" (PDF). Concrete Repair Bulletin. 28 (6): 9–13. November 2015.

• Historic American Engineering Record (HAER) No. IL-157, "St. Charles Air Line Bridge"
• Historic Bridges of Michigan and Elsewhere
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