The Gateway Arch turned 50 with the help of modern materials and math.

When creating a monument for future generations to behold, there are two features it must possess—simplicity and permanence.  This was the thinking that architect Eero Saarinen used when designing the “Gateway Arch to the West,” which celebrated its 50th anniversary October 28, 2015. Saarinen gained inspiration by looking to the nation’s capital. He surmised that timelessness arose from geometric forms—the Washington Monument is an obelisk; the Lincoln Memorial is a rectangle; and the Jefferson Memorial is a circle in a square. So, Saarinen selected an arch.

However, this arch would be no ordinary arch. Aloft at 630 feet, it had a special geometric form that moved mathematicians and masons—the catenary arch.  A catenary arch appears when a chain hangs freely from two supported ends and occurs in everyday life from draping power lines to necklaces.  When inverted, this arch supports its own weight and differs from a parabola. A catenary arch has steeper legs, a flatter peak, and greater strength. With this appointed shape, Saarinen next sought to find the right building materials to make it.

He chose a material that would represent the modern age—stainless steel. This metal was first created in the 19th century, but perfected in the 20th. It is composed of steel (a combination of iron and carbon) with a dash of chromium. The mix of iron and carbon gives the metal strength, but chromium provides longevity by overcoming iron’s weakness of rusting.

Rust never sleeps, as songwriter Neil Young once penned.  So, the best way to stop it is to prevent it. Paint is one way to halt rust, but an atomic layer of protection helps too. This is where chromium comes in. Chromium makes a thin layer of chromium oxide on the surface, which hinders water from combining with the iron to create rust.

The path to developing the metal for the Gateway Arch was circuitous at best. Stainless steel wasn’t a creation, but an evolution. The discovery of chromium occurred in the 18th century by French chemist Louis Nicolas Vauquelin.  However, the secret to making lasting metals would take some time, as it puzzled some of the world’s greatest minds. Michael Faraday, one of history’s best scientists, began his career investigating new kinds of steel in the 1820s. He had limited success.

Other delays occurred. There were unfiled patents in the 1870s on weather-resistant metals. Then efforts stalled. Two decades later, there was a renewed interest to create stainless steel, but it took a wrong turn. A famous scientist, Sir Robert Hadley, erroneously concluded in the 1890s that chromium lessened steel’s ability to fight corrosion. His unfortunate claim curtailed future work, until Harry Brearley serendipitously uncovered that chromium makes steel “rustless” and commercialized it as cutlery, which was announced in The New York Times in 1915. All these steps together made Saarinen’s Gateway Arch possible.

The stainless steel in the Gateway Arch is the same in a household fork. Metal plates (as thick as four nickels) are held together with miles of welds making the arch’s exterior nearly 900 tons. (For comparison, the Chrysler Building has a 27-ton stainless exterior.) The arch is perched on the edge of the Mississippi where an early trading outpost stood, which was frequented by pioneers, fur traders, and explorers before heading westward. In the 1930s, city leaders wanted to transform this decaying site with a monument to honor those who “won” the west, the Louisiana Purchase, and Thomas Jefferson.

Saarinen’s application in 1947, one of 172 entries including one from his famous architect father, captured what these leaders had envisaged—a message to the future, with modern materials, and a wink to the past, with a simple geometric form. Construction did not begin until 1962. Sadly, Saarinen died of a brain tumor in 1961 and never got to see his structure.

Today, the arch stands strong, although it contends with dirt and chemical pollution from industrial emissions from the arch’s early years. These practices are no longer permissible with the establishment of the Clean Air Act in the 1960s. The survival of the arch is not only a testament to stainless steel but to progressive legislation.  The Gateway Arch continually serves as a material, design, and cultural zeitgeist—relevant to the present, but also connecting us to the past as it propels us upward and forward.

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