Gateway Arch: The Design That Sustains St. Louis

Missouri’s Gateway To The West

St. Louis’ most iconic landmark, The Gateway Arch, is a structural expressionist monument located on the west bank of the Mississippi River in St. Louis, Missouri. Completed in 1965, the arch is the tallest memorial in the United States and the tallest stainless steel monument in the world. The arch positioned 630 ft above the Mississippi River, is the world’s tallest arch. The monument built as a westward expansion in the United States stands above the Old Courthouse and the Jefferson National Expansion Memorial park and museum.

The visionary Thomas Jefferson negotiated the Louisiana Purchase in 1803, doubling-up the area covered under the United States. The explorers, Lewis and Clark, and their Shoshone guide Sacagawea, explored the new territory and delineated a path to the Pacific Ocean. The challengers, Dred and Harriet Scott, filed suit at the Old Courthouse for their independence from slavery, and St. Louis suffragette Virginia Minor sued for women’s right to vote. The Finnish-born artist and architect Eero Saarinen designed the monument, the Gateway Arch, which honours them.

Eero Saarinen, a champion of the neo-futuristic style, designed the celebrated engineering victory and America’s tallest national monument, the Gateway Arch. As a constituent of the Jefferson National Expansion Memorial, the Gateway Arch is more than steel; it celebrates the accomplishments of nineteenth century westward pioneers who helped shape its history, and the city’s role as the ‘Gateway to the West’. The Gateway Arch National Park (formerly known as the ‘Jefferson National Expansion Memorial’), was founded by the National Park Service in 1935 to commemorate Thomas Jefferson’s vision of a transcontinental United States.

Today, the Gateway Arch commemorates the diverse people who shaped the region and the country. It epitomizes the design’s interrelationship with technology. The brilliant nature of this design posed some particularly unique challenges to all involved from conception through construction, and into daily operation. Saarinen was criticized by his contemporaries for lacking a distinctive vision and style like many of his peers; however, the recent years have seen resurgence in admiration for his works for precisely the lack of a unique aspect in his works. The modern architects and critics rather than viewing his work as lacking vision, acknowledge the pluralistic approach as a project-by-project flexibility that served the project while being true to an overarching aesthetic of clean, and revolutionary lines. The arch’s architect is considered one of the masters of American 20th century architecture.

A Brief History

The plans for the arch were first visualized in 1933 by the civil leader Luther Ely Smith. Smith, who strived to revive the waterfront, suggested his plan in a meeting with city leaders. The idea for the Gateway Arch was conceived as a part of the Jefferson National Expansion Memorial (JNEM). Consequently, by 1935, the Jefferson National Expansion Memorial Association (JNEMA) was formed. The JNEMA intended to complete Smith’s idea with a public memorial that would emphasize the actions of early westward pioneers, particularly President Thomas Jefferson (for the Louisiana Purchase of 1803), Lewis and Clark, and other great builders of the nation that supported the development of St. Louis.

In 1935, the President Franklin D. Roosevelt selected property along the St. Louis riverfront to be developed as the Jefferson National Expansion Memorial (now known as Gateway Arch National Park). The land was cleaned for construction, and the St. Louis city deeded the Old Courthouse for the National Park Service to be integrated into the Memorial. In 1948, a national design competition determined the design of the new monument. The Finnish-born architect Eero Saarinen who received his education in the US was selected as the winner with his design for a stainless steel arch. It took more than a decade to clear the arch’s designs past state and federal governing bodies and to negotiate construction crews and costs. Saarinen, who was working at the time to perfect his design, unfortunately, did not live to see the construction of the arch; he died of brain tumour in 1961.

Upon its completion, the Gateway Arch cost $13 million (equivalent to $190 million in 2015). However, owing to budget constraints, Saarinen’s full design for the grounds was not realized. The Gateway Arch stands as a symbol of national identity and an iconic example of mid-century modern design. Since its completion in 1965, it has become a popular tourist attraction and a defining symbol of the city of St. Louis, and receives nearly four million visitors every year.


The construction was postponed during World War II. The ground for the arch was first broken on June 23, 1959, and the foundations were laid in 1961. The excavations continued until the construction of the Gateway Arch began on February 12, 1963, as the first steel triangle for the south leg was moved into place.

The steel triangles, which became narrow as they spiralled to the top, were positioned using a group of cranes and derricks. The positioning into place was followed by filling each section with concrete and prestressing with 252 tension bars. Further, a scissors truss was placed between the partially-completed legs at 160 m (530 ft), to keep them stable; as the derricks were dismantled later, scissors truss was removed.

The construction process was delayed by a combination of financial issues, safety checks and legal disputes. Additionally, as African-American workers were working on the project, civil rights activists brought work to a stand-still and strikes were held in protest against the discrimination of African-Americans.

The foundation stone was a 2.4 m (8 ft) long triangular section. To attenuate thermal expansion, which had compressed the gap at the top by 13 cm (5 inches), fire hoses were used to spray water to cool the surface and help it contract. The placement of the foundation stone was followed by prying the legs apart 1.8 m (6 ft), using a hydraulic jack, with the final section being inserted to secure the arch.

Despite the delays and hindrances, the arch was finally topped out on October 28, 1965. In June 1967, the internal elevator system to take visitors to the top and the Visitor Center, which included exhibits, opened to the public. Less than a decade later, the Museum of Westward Expansion opened underneath the arch with exhibits on St. Louis’ role in the rapid westward expansion of the 19th century.


Eero Saarinen conceived the monument being clad in stainless steel and built in the form of an inverted, weighted catenary arch, a shape that would be formed by a heavy chain hanging freely between two supports. The lack of an orthogonal internal regularity prompted the conventional construction methods inappropriate for this constantly curving structure.

The catenary construction, St. Louis’ Gateway Arch, has no structural frame, and instead counts on its own skin for support. The double-walled structure rises 630 ft into the air through triangular segments steadily declining in size from 54 ft per side to 17 ft. It comprises of stainless steel and carbon steel plates. The steel plates are assembled very tightly against each other in order to increase its structural stability and to increase its aesthetics - making it look even more slender than it is. In addition to strengthening and post-tensioning rods, the double-walled sections for the first 300 ft contain concrete, while the sections above integrate steel framing. Complex mathematical equations were necessary to ensure the arch design would work, and the base of each leg at ground level had an engineering tolerance of just 0.4 mm (1/64 inch) to ensure they would meet at the top.

Truly colossal in scale, the arch’s legs stand 630 ft apart from each another, i.e., more than two football fields. The arch spans 192 m (630 ft) between the outer faces of its triangular legs. Each leg is an equilateral triangle, narrowing from 16 m (54 ft) per side at the base to 5.2 m (17 ft) at the top. Further, they are embedded in concrete foundations 13 m (44 ft) thick and 18 m (60 ft) deep. Also, each leg contains a stainless steel skin covering two carbon-steel walls with reinforced concrete filled between them. This continues until 91 m (300 ft); following that, carbon steel stiffeners are used instead of concrete. These inner and outer stressed-skins join to form a composite structure which carries the self weight and wind loads to the ground.

Further, there are 1,076 stairs, though they are only for emergency purposes and for maintenance. The windows in the observation deck are only 7-inches by 27-inches. This is because larger windows would not have been able to stand the pressure that was used to jack the legs apart. The arch is earthquake-resistant and is designed to sway up to 46 cm (18 inches) in either direction, while withstanding winds of up to 150 miles per hour.

Moreover, the arch is hollow and accommodates a complex system of elevator cars that climb diagonally to the top of the curved arch carry 12 people at a time to the top where visitors can view the surrounding landscape from 630 ft above the ground. Operating at the rate of 340 ft per minute, the ride takes 10 minutes for the full trip. The observation platform is 65 x 7 ft, and fitted with plate-glass windows that provide views to the east and west. These elevator cars were designed as futuristic pods that were inspired by the similar aesthetics of the time.


The Arch Today

The arch since its completion has been the subject to several improvements, including illuminating floodlights, the Grand Staircase, and a modernized museum. Now, the Jefferson Expansion Memorial comprises the Gateway Arch, the Museum of Westward Expansion, and the Old Courthouse. Today, the arch has a number of attractions for visitors to experience. Not only can they ride one of the two trams to the observation deck at the top of the monument, but the four minute ride is also narrated.

In addition, tourists may visit the Museum of Westward Expansion in the Visitor Center, which is located underground. There are also two theatres located in the Visitor Center. The original theatre was built in 1972 and the newer theatre, which is called the Odyssey Theatre, has a four story screen and was built 20 years later. A new entrance to the visitor center at the Gateway Arch in St. Louis has been constructed as part of a $380 million project to improve the 91-acre Jefferson National Expansion Memorial.




Amrita Batra
Associate Editor
Civil Engineering and Construction Review