Working on his own, Ammann had developed another scheme. Quietly, he wrote to the governor of New Jersey with suggestions for a smaller, cheaper suspension bridge to be built across the Hudson at 179th Street. The newly formed Port of New York Authority, which enjoyed both states' cooperation and had a short time before rejected Lindenthal's expensive monstrosity, was immediately interested — to Lindenthal's understandable dismay. "Now it appears that A. has used his position of trust, the knowledge acquired in my service...to compete with me in plans for a bridge over the Hudson and to discredit my work on which I had employed him," Lindenthal wrote despairingly to the governor. "He does not seem to see that his action is unethical and dishonorable."
But new forces were at work. With construction under way for what would be known as the Holland Tunnel, it was assumed that connecting the metropolis to its burgeoning New Jersey suburbs by underwater routes would be cheaper than a bridge (a notion proved wrong well before the tunnel's 1927 completion). By that time, too, necessarily heavy (and expensive) railroad spans across the Hudson were steadily being eclipsed by less costly ones dedicated to a newly popular conveyance: the car. Already, in Philadelphia and Detroit, huge suspension bridges had been built for cars. The future was clear.
By 1925, Ammann was bridge engineer for the Port Authority, charged with designing not only the 179th Street bridge (then known as the Hudson River Bridge) but also a bridge between Staten Island and New Jersey—both mainly for cars. Construction of the Hudson bridge began in the fall of 1927, with more than 100,000 miles of cable wire strung across the river by John Roebling's company.
By any standard, the bridge was monumental. With a 3,500-foot main span — nearly twice that of the next largest suspension bridge, built just two years before — its slender deck was to arch gracefully more than 200 feet above the Hudson. Its twin 604-foot towers would stand nearly 50 feet taller than the Washington Monument. And each of its four cables could support more than 90,000 tons — ten times more than each Brooklyn Bridge cable.
For his design, Ammann owed as much to material advances since that 1883 wonder as he did to his own ingenuity. Improved steel ensured that when drawn to only 0.196 inch in diameter, each of the 26,474 wires that made one cable had a strength of at least 240,000 pounds per square inch—more than one and a half times that of the cable wires in the Brooklyn Bridge. And better machinery allowed the wires to be hung from the towers (a process called spinning) 16 times faster than in 1883. Engineers followed what they had learned from the behavior of their model, that ten-foot section of cable today in the Smithsonian's collections, to compress the wires together into their final, three-foot-diameter, cylindrical form.
In the relentless Great Depression, the bridge became a sort of savior in steel. Completed six months ahead of schedule, it cost less than the $60 million originally allocated. "Fulfilling a dream of three-quarters of a century," ran the ecstatic headline in the New York Times. On October 24, 1931, in front of thousands of spectators, New York governor (and soon to be President) Franklin Roosevelt and New Jersey governor Morgan Larson opened the bridge, newly named in honor of George Washington. In tribute to his mentor, Ammann drove with Gustav Lindenthal onto the bridge that the older man had spent his lifetime fruitlessly dreaming of.
Even more revolutionary than its length was the bridge's lack of a common design feature. Until the George Washington, modern suspension bridges were stiffened with steel trusses and beams to limit motion in traffic and wind (an important consideration when a bridge's length is large relative to its width and depth, like the George Washington's). But such stiffening often gave bridges less attractive, thicker decks — and added cost. Ammann reasoned that the sheer weight of his span, and its necessarily heavy cables, would by themselves provide sufficient stiffness.
The George Washington's resulting slender profile — both from the side as well as from above — fueled engineers' aesthetic sensibilities. Just six years later, the Golden Gate Bridge astounded the world with a narrower and yet even longer span. If such gracefully thin and relatively light bridges were sometimes disconcertingly flexible in a breeze (as drivers and engineers noted), they also were lovely to look at.
In 1940, however, the extremes of Ammann's innovation were dramatically demonstrated in the wind-driven collapse of the aptly nicknamed "Galloping Gertie," otherwise known as the Tacoma Narrows Bridge. After his investigation of that famous failure, which had been captured on film for the nation to see, Ammann wrote, "Its smaller weight and extreme narrowness has drastically revealed that this practice has gone too far."
By the early 1960s, when the George Washington's lower deck was added (as specified in the original plans), Ammann had all but eclipsed his mentor. Ammann's other 1931 creation, the Bayonne Bridge connecting Staten Island and New Jersey, was until 1977 the world's largest steel arch bridge — more than 600 feet longer than the previous record holder, Lindenthal's Hell Gate Bridge.