Tacoma Narrows Bridge. This bridge, constructed across the stretch of Puget Sound known as the Narrows, between Tacoma, Washington, and the Olympic Peninsula, was torn apart in the wind on November 7, 1940, only four months after it was opened.

Designed to accommodate just two lanes of traffic in a then sparsely populated area, the bridge deck was narrow as well as shallow, being supported, for reasons of economy and aesthetics, by plate girders rather than a more conventional deep truss. This meant that the deck's resistance to bending and twisting was uncommonly low. When the wind blew in a certain way, the roadway undulated up and down, thus earning the bridge the nickname Galloping Gertie. After about four months, torsional oscillations began when there was the dislocation of a cable at mid-span. The amplitude of the oscillations was magnified by a phenomenon known as wind-structure interaction, and eventually the aerodynamic forces on the deck were of such a magnitude that its center span broke up and fell into the water.

Because the Tacoma Narrows Bridge had demonstrated unexpectedly large motions from the outset, it had already been the subject of study. When the rhythmic twisting began, cameras were set up and thus the failure of the bridge that occurred only hours later was captured on film. This footage, along with other made under the direction of Frederick Burt Farquharson (1895–1970), a professor in the University of Washington's Department of Civil Engineering who had been studying the behavior of the bridge, soon became a classic.