Which U.S. bridge collapsed in 1940 just months after opening because of wind-induced torsional motion?

The 1940 Tacoma Narrows Bridge was the U.S. bridge that collapsed after wind-induced torsional motion just months after opening.

The suspension bridge crossed the Tacoma Narrows in Washington State and opened to traffic on 1 July 1940. Its slender deck began moving dramatically in moderate winds, earning the nickname “Galloping Gertie.” On 7 November 1940, twisting oscillations grew until the central span broke apart and fell into the water.

The collapse became a landmark case in structural engineering and is widely used to explain aeroelastic flutter and torsional instability. The bridge’s failure was not simply caused by the wind speed alone; its narrow, flexible deck and insufficient aerodynamic stability were central factors. A replacement Tacoma Narrows Bridge opened in 1950, and the original collapse led engineers to pay much greater attention to wind-tunnel testing and aerodynamic behavior in long suspension bridges.