Opened July 1, 1940, the Tacoma Narrows Bridge was the world’s third-longest suspension span and so slender its roadway could ripple in light wind. Four months later, aerodynamic instability and inadequate damping turned it into a twisting steel ribbon before the center span fell into Puget Sound. Engineers had built elegance, motion, and a four-month warranty.
Sources: Washington State Department of Transportation · WSDOT: A Tale of Three Bridges
Image: Barney Elliot / Prelinger Archives, public domain, via Wikimedia Commons.