The Gateway Arch National Park, standing tall at 630 feet, formerly known as the Jefferson National Expansion Memorial until 2018, is an American national park located in St. Louis, Missouri, near the starting point of the Lewis and Clark Expedition. The Gateway Arch and its immediate surroundings were initially designated as a national memorial by executive order 7523 on December 21, 1935, and redesignated as a national park in 2018. The park is maintained by the National Park Service (NPS).
The memorial was established to commemorate:
- the Louisiana Purchase, and the subsequent westward movement of American explorers and pioneers;
- the first civil government west of the Mississippi River; and
- the debate over slavery raised by the Dred Scott case.
The park consists of a 91-acre (36.8 ha) park along the Mississippi River on the site of the earliest buildings of St. Louis; the Old Courthouse, a former state and federal courthouse that saw the origins of the Dred Scott case; the 140,000 sq ft (13,000 m2) museum at the Gateway Arch; and most notably the Gateway Arch, a steel catenary arch that has become the definitive icon of the city.