The Gateway Arch is a 630-foot (192 m) monument in St. Louis’ role in the Westward Expansion of the United States during the nineteenth century. The park is a memorial to Thomas Jefferson’s role in opening the West, to the pioneers who helped shape its history, and to Dred Scott who sued for his freedom in the Old Courthouse. It is the world’s tallest man-made monument.
The Arch was designed by Finnish-American architect Eero Saarinen in 1947 and construct began on February 12, 1963, and was completed on October 28, 1965. The Gateway Arch opened to the public on June 10, 1967.
The arch is 630 feet (192 metres) tall, and the distance between its two legs is equal to its height. Inside are two trams, each of which consists of eight cars that each carry up to five seated people at a time. Visitors can take a four-minute tram ride to the viewing platform at the top of the arch. Sixteen windows face east, and the same number face west for views of the city, river, and surrounding land. At the base of the arch, the Museum of Westward Expansion features displays showing what life was like in the 1800s, as well as exhibits on the construction of the arch.
The Gateway Arch is a part of the Jefferson National Expansion Memorial. It was named for U.S. Pres. Thomas Jefferson, who was responsible for buying a large area of what became the western United States in the Louisiana Purchase of 1803. To explore that land, the Lewis and Clark Expedition set out from St. Louis in 1804. In addition to the Gateway Arch and its museum, the memorial site includes the Old Courthouse, where the first two trials that led to the Dred Scott decision were held.
The windows of the observation deck are located around the apex of the arch. Both the width and height of the arch are 630 feet (192 m). The arch is the tallest memorial in the United States and the tallest stainless steel monument in the world. The cross-sections of the arch’s legs are equilateral triangles, narrowing from 54 feet (16 m) per side at the bases to 17 feet (5.2 m) per side at the top. Each wall consists of a stainless steel skin covering a sandwich of two carbon-steel walls with reinforced concrete in the middle from ground level to 300 feet (91 m), with carbon steel to the peak. The arch is hollow to accommodate a unique tram system that takes visitors to an observation deck at the top. The structural load is supported by a stressed-skin design. Each leg is embedded in 25,980 short tons (23,570 t) of concrete 44 feet (13 m) thick and 60 feet (18 m) deep. Twenty feet (6.1 m) of the foundation is in bedrock. The arch is resistant to earthquakes and is designed to sway up to 18 inches (46 cm) in either direction, while withstanding winds up to 150 miles per hour (240 km/h). The structure weighs 42,878 short tons (38,898 t), of which concrete composes 25,980 short tons (23,570 t); structural steel interior, 2,157 short tons (1,957 t); and the stainless steel panels that cover the exterior of the arch, 886 short tons (804 t). This amount of stainless steel is the most used in any one project in history. The base of each leg at ground level had to have an engineering tolerance of 1⁄64 inch (0.40 mm) or the two legs would not meet at the top.