On November 7, 1940, just four months after its completion, the world’s third-longest suspension bridge snaps in a 42 mph wind and collapses into the waters below. This was the Tacoma Narrows Bridge, a slender, 2-lane creation whose tendency to visibly sway and wobble earned it the name “Galloping Gertie.”
A single car was on the bridge at the time of the incident, occupied by a newspaper copy editor named Leonard Coatsworth and his cocker spaniel. When the bridge began to violently tip one way and then the other, he abandoned the car—and, after a quick, failed coercion effort, the dog—and crawled his way across the bridge to shore before the bridge snapped. (You can read a full account of his experience in his own words here.)
The dog, still inside the car when it slid off the broken bridge, was the single casualty of the disaster.
Though a firm consensus hasn’t been reached as to the exact reasons for the collapse, the Tacoma Bridge incident led to better aerodynamics in bridge design and, eventually, the implementation of mandatory wind-tunnel testing. In 1950, a new and improved Tacoma Narrows Bridge (nicknamed “Sturdy Gertie”) was constructed with wider lanes and better resistance to wind.