The Gateway Arch

Podcast Transcript

In the midst of the Great Depression, the City of St. Louis wanted to create a monument to the city’s role in the westward expansion of the United States and for general waterfront improvement.

It took thirty years, but they eventually created their monument with the assistance of the Federal Government. When it was completed, it was a structure like no other on Earth.

It was a 630-foot-tall freestanding stainless steel arch. It required innovations not just in design and architecture, but in materials, construction, and even elevators.

Learn more about the Gateway Arch, how and why it was built, on this episode of Everything Everywhere Daily.

To understand why the Gateway Arch was built, we first need to understand the city of St. Louis.

St Louis used to be a much bigger deal, relatively speaking, than it is today. This was due to its strategic location at the confluence of the Mississippi and Missouri Rivers.

There was a time when St. Louis wasn’t a midwestern city. It was a Western city. In fact, it was really ‘the’ western city. Until the Dodgers moved to Los Angeles in 1957, the St. Louis Cardinals were the westernmost team in Major League Baseball.

Founded by French fur traders in 1764, it grew into a key river port where goods, supplies, and people gathered before heading into the frontier. During the early 19th century, it became the base for the Lewis and Clark Expedition, which departed from near St. Louis in 1804 to explore the newly acquired Louisiana Territory as part of the Louisiana Purchase.

As steamboats began to ply the Mississippi and Missouri Rivers, St. Louis evolved into a bustling hub linking eastern markets with the expanding territories to the west. Traders, trappers, and settlers all passed through its warehouses and docks, making it both the commercial and symbolic “Gateway to the West.”

Fast forward to 1933.

The American West has largely been settled. St. Louis is no longer in the West, but rather the Midwest.

With the Great Depression in full swing, communities around the country, as well as the Federal government, were building public works projects as a means of creating jobs.

In the case of St. Louis, they also had another problem. The area near the Mississippi River had deteriorated into a collection of abandoned warehouses and dilapidated buildings. This area, which had once been the busiest and most important commercial part of town, was now a blight and an eyesore.

In 1933, civic leader Luther Ely Smith conceived the idea of creating a memorial on the riverfront that would celebrate St. Louis’s pivotal role in westward expansion and simultaneously revitalize the area.

Mayor Bernard Dickmann convened business and civic leaders who formed the Jefferson National Expansion Memorial Association, then pursued federal partnership and local bonds. President Franklin D. Roosevelt approved the project in 1935 and empowered the Interior Department to acquire the site.

After a series of court battles, the government initiated the condemnation and demolition of dozens of riverfront blocks in 1939 to clear the land for the memorial.

The project faced immediate challenges, including the need to clear forty blocks of historic riverfront buildings, a controversial decision that required the demolition of structures dating back to the city’s founding.

During World War II, the project stalled as national resources were diverted to the war effort. However, in 1945, momentum resumed when the Jefferson National Expansion Memorial Association announced a nationwide competition to design the memorial.

This competition drew 172 entries from architects and designers nationwide.

In 1947, a Finnish-American architect named Eero Saarinen submitted a design featuring a massive stainless steel arch. Saarinen, who was only 37 years old at the time, proposed a sleek, modernist structure that would rise 630 feet into the sky, making it the tallest monument in the United States. His design was revolutionary in its simplicity and elegance, rejecting traditional memorial aesthetics in favor of a pure, abstract form.

The jury unanimously selected Saarinen’s design, praising its “profound and beautiful statement” that would “have lasting significance and would be a landmark of our time.”

Here, I need to digress a bit about the shape of the arch. Many people think that it is the shape of a parabola.

It is not.

It is, in fact, a precise mathematical form known as a weighted catenary. A catenary is the shape that a perfectly flexible, uniform chain or cable assumes when suspended freely under its own weight between two points.

When such a curve is turned upside down, it provides an ideal form for a freestanding structure, efficiently distributing weight and internal forces through compression rather than tension.

The reason why it is called a weighted catenary instead of just a normal catenary is that its curve is adjusted to account for the Arch’s varying thickness. It is broader at the base, at 54 feet wide, and narrows toward the top, where it is 17 feet wide.

Eero Saarinen and structural engineer Hannskarl Bandel designed it this way so that the stresses throughout the stainless-steel and concrete structure would be distributed evenly, allowing the Arch to bear its own weight gracefully.

Construction began on February 12, 1963, after years of funding, contracting, and preparatory work.

Building the Gateway Arch presented an extraordinary set of engineering and materials challenges that tested the limits of mid-20th-century design and construction. From the outset, the monument required precision on a scale that had rarely been attempted before.

Its shape meant that even minute misalignments during construction could lead to catastrophic structural failure when the two halves met at the apex. Every technical decision, from the choice of materials to the method of assembly, had to ensure both mathematical exactness and physical durability.

The first challenge was geometry. The Arch’s two legs were built independently from massive concrete foundations sunk deep into the Mississippi River floodplain. Each leg rose as a triangle of steel boxes, narrowing as it ascended.

Because the curve’s alignment depended on exact measurements, surveyors had to monitor every inch with extreme precision using optical and electronic distance measurements.

If the two legs were off by more than half an inch when nearing the top, they would not meet correctly. As the final sections approached each other, engineers sprayed water to cool one leg and allow the metal to contract slightly, bringing them into perfect alignment before placing the keystone section on October 28, 1965.

Material selection posed its own set of problems.

The Arch’s skin is made of 900 tons of Type 304 stainless steel, chosen for its corrosion resistance and long-term stability. However, stainless steel had rarely been used for such a large structural surface, and it had to be fabricated into curved triangular panels with both precision and strength.

Each outer skin panel was welded to an inner carbon-steel framework, creating a double-walled system that was then filled with reinforced concrete up to a certain height for stiffness. The changing cross-section meant that no two steel segments were alike, and fabrication required custom molds for each section.

Construction logistics were equally complex. Because scaffolding was impossible at such heights and curvatures, engineers from the Pittsburgh-Des Moines Steel Company devised custom climbing cranes that inched upward along each leg, lifting prefabricated triangular sections into place.

Workers bolted and welded these sections together hundreds of feet in the air, where wind sway and temperature shifts could subtly alter alignment.

In addition to all this, there is an observation deck at the top of the arch, and a system had to be designed to transport people to the summit.

The elevator inside the Gateway Arch is actually a unique tram system rather than a conventional vertical lift. Because the Arch curves and narrows as it rises, a standard elevator could not operate inside it.

To solve this, the National Park Service commissioned engineer Dick Bowser in 1962 to design a system that could safely carry visitors to the observation room at the top while following the Arch’s inner curvature.

Bowser’s solution combined elements of an elevator, an escalator, and a Ferris wheel. He designed small, cylindrical tram cars that each hold five people. The cars are linked into trains that travel up and down inside each leg on parallel tracks.

As the tram ascends, the cars pivot like a Ferris wheel, allowing passengers to remain upright even as the track curves inward toward the apex. The journey takes about four minutes each way, with the system constantly adjusting to the Arch’s changing slope.

The Gateway Arch was officially completed and dedicated on October 28, 1965, though public access to the top didn’t begin until July 1967. The dedication ceremony, held on May 25, 1968, featured Vice President Hubert Humphrey and drew hundreds of thousands of visitors.

The completed structure stood as the tallest man-made monument in the United States and the tallest stainless steel structure in the world.

The memorial’s costs reflected the scale and complexity of the undertaking. The arch itself cost approximately $13 million to construct, which is equivalent to over $130 million today when adjusted for inflation. The entire Jefferson National Expansion Memorial, including the Museum of Westward Expansion, built underground beneath the arch and the surrounding grounds, required significantly more investment.

However, the inflation-adjusted cost is deceiving. In 2018, the grounds, not the arch itself, underwent a $380 million refurbishment, including rerouting a highway. It is highly unlikely that building a similar structure today could cost anything less than a billion dollars.

The same year the renovation was complete, Congress redesignated the former Jefferson National Expansion Memorial as Gateway Arch National Park, a change signed into law on February 22, 2018.

The renaming formalized what the public had long called the site and coincided with the completion of the new museum and landscape. However, the shift from “national memorial” to “national park” also sparked debate over naming standards in the park system.

Gateway Arch National Park is by far the smallest site with a national park designation in the United States, at only 90 acres. The next smallest park is Hot Springs National Park in Arkansas, at 5,548 acres, over 61 times larger.

If you are curious, the largest National Park in the US is Wrangell–St. Elias in Alaska, which is 92,479 times larger.

On a personal note, I’ve been to the Gateway Arch several times, and it is one of my favorite structures in the world. I highly recommend visiting if you are in St. Louis, and take the time to watch the video, which documents its construction.

Definitely take the tram to the top of the arch, where you can not only see the city, but also experience the most unique vertical transportation system on Earth.

In addition to visiting the top of the arch, I recommend standing underneath it, which is something that you can do. It is a very surreal experience standing directly below the arch, looking up, and seeing a massive structure 630 feet above your head looming over you.

I don’t know if there is anything else on Earth where you can experience something like that.

Eero Saarinen died in 1961 at the age of 51, before he was able even to see the start of construction of his greatest design. In addition to the arch, he also designed Dulles International Airport, the St. Louis Lambert Airport Terminal, the auditorium and chapel at MIT, the CBS building in New York, and the TWA Flight Center at JFK International Airport.

Over the decades since its completion, the Gateway Arch has become synonymous with St. Louis itself, appearing in countless photographs, films, and television shows.

It has welcomed millions of visitors who have ridden the tram to the top for panoramic views stretching up to thirty miles on clear days. The monument serves not only as a tourist attraction but also as a source of civic pride and a symbol of American innovation and ambition.

The Executive Producer of Everything Everywhere Daily is Charles Daniel. The Associate Producers are Austin Oetken and Cameron Kieffer.

I have a correction to make. In the episode on Bhutan, it was correctly pointed out to me that there are no lemurs in Bhutan. Lemurs are only found in Madagascar.

I was sloppy. Bhutan has members of the suborder Lemuriformes, which is a suborder that includes lemurs. In Bhutan, this consists of the Bengal slow loris.

Related to the lemur, but not a lemur.

Mea culpa, mea culpa, mea maxima culpa.

Today’s review comes from listener colleneelloc over on Apple Podcasts in the United States. They write:

Very informative!

I love the wide variety of topics – learn something new every time! I love how they are short, so I can listen while getting ready, etc., working on the back catalog now.

Thanks, Colleneelloc! I wish you luck in your pursuit of completionist club membership. When you achieve your goal, we will be waiting for you with open arms at the clubhouse.

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