There can be few more dramatic ways of winning over a skeptical audience than the method chosen by John Robinson on 14 June 1874, to highlight the sturdiness of a newly constructed bridge. Upon completion of the revolutionary Eads Bridge, constructed to connect St Louis and East St Louis on opposite banks of the Mississippi River, Robinson made the decision to walk a fully-grown elephant across its length, thus demonstrating its suitability for heavy traffic.
Crowds gathered on either side of the bridge to watch the spectacle, cheering wildly as the elephant, borrowed from a traveling circus that happened to be passing through the area, made its way gingerly across the vast expanse. It was widely believed that elephants had in innate feeling for danger, and that it would have refused to cross if it sensed the bridge was unsafe. This “test” duly passed, the bridge was deemed sound, although further demonstrations were conducted to prove its mettle, including driving a convoy of twenty steam locomotives back and forth across its length.
The Eads Bridge was revolutionary in its design, being the first bridge in America of significant size to be constructed using steel girders and a cantilever form. It was named after its designer, the engineer James B. Eads, who also oversaw the seven-year construction process. Upon completion, the Eads Bridge was the longest arch bridge in the world, its three great steel arches measuring nearly almost 2,000 metres (6,500 feet) in length. It had two levels, the lower used for rail traction, and the upper for road vehicles and pedestrians.
Owing to its unique geographical constraints, the construction project was not a simple one. The variable density of the riverbed meant that the huge granite piers that support the arches required incredibly deep foundations, being almost forty metres below the water level at some points. The bridge was also unusually high, as local steamboat operators had successfully lobbied for high clearance levels, in order that their vessels could pass under the bridge unhindered.
The bridge was officially inaugurated on 4 July 1874, and despite the difficulties of construction was immediately hailed as an aesthetic and architectural, if not financial, success. For its graceful lines and epic proportions it quickly became an icon of the city, and was marveled over for its precision engineering.
Although it is no longer the sole crossing of the Mississippi in St Louis, the Eads Bridge remains a vital part of the infrastructure of the city. The surface underwent major restoration in the 1990s, and the bridge now accommodates a four-lane highway, as well as the tracks of the St Louis rapid transit system, Metrolink.