A paddlewheel on the Mississippi River echoes the shape of the Gateway Arch, in St. Louis, the tallest arch in the world.
Photograph by Sam Abell, National Geographic

Download this file

  • Select Text Level:

    On October 28, 1965, the Gateway Arch in St. Louis, Missouri, was completed. The arch is a monument to westward expansion in the United States, particularly the Lewis and Clark expedition that embarked from St. Louis in 1804 to explore the Louisiana Territory. Today, the Gateway Arch is the tallest arch in the world, standing 192 meters (630 feet).
    The Gateway Arch was designed by the Finnish-American architect Eero Saarinen. Saarinen was inspired to create an innovative design to represent the “modern age.” “Neither an obelisk nor a rectangular box nor a dome seemed right on this site or for this purpose. But here, at the edge of the Mississippi River, a great arch did seem right.” 
    The Gateway Arch remains the most striking symbol of the “Gateway to the West.” It is the centerpiece of a national park—the Jefferson Expansion Memorial, named after the president (Thomas Jefferson) who made the Louisiana Purchase.
  • Term Part of Speech Definition Encyclopedic Entry
    arch Noun

    shape that looks like an upside-down "U."

    architect Noun

    person who designs buildings or other large structures.

    astrogeology Noun

    study of the physical history and structure of planets and moons.

    complete Verb

    to finish.

    concrete Noun

    hard building material made from mixing cement with rock and water.

    construct Verb

    to build or erect.

    dome Noun

    shape that is half of a sphere.

    Encyclopedic Entry: dome
    embark Verb

    to leave or set off on a journey.

    encase Verb

    to enclose or completely confine.

    engineer Noun

    person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).

    expansion Noun

    process of enlarging.

    expedition Noun

    journey with a specific purpose, such as exploration.

    innovative Adjective

    new, advanced, or original.

    inspire Verb

    to influence to act.

    monument Noun

    large structure representing an event, idea, or person.

    national park Noun

    geographic area protected by the national government of a country.

    obelisk Noun

    tall, tapering, four-sided stone structure.

    represent Verb

    to stand for a person, community, or idea.

    steel Noun

    metal made of the elements iron and carbon.

    symbol Noun

    something used to represent something else.

    tram Noun

    vehicle or car carried by an overhead carrier.