Jefferson National Expansion Memorial is the federal park holding the Gateway Arch and the grounds along the riverfront. The memorial was authorized by Congress in 1935, during the Depression, as a public works project and a monument to Manifest Destiny — the 19th-century American belief that the United States was destined to expand across the continent from sea to sea. The choice of Thomas Jefferson's name for the memorial was deliberate: Jefferson negotiated the Louisiana Purchase in 1803, and his vision for an 'Empire of Liberty' stretching westward is both the ideological foundation of the park and a source of ongoing historical debate.
Jefferson, the author of the Declaration of Independence and a prophet of liberty, was also a slaveholder who held more than 600 people in bondage over the course of his lifetime. The westward expansion he championed depended on the dispossession of Native peoples across the continent. The memorial was redesigned and its underground museum renovated in 2018, and the new Gateway Arch National Park museum engages more honestly with these contradictions than any previous iteration did.
The park name was changed in 2018 from 'National Expansion Memorial' to 'Gateway Arch National Park.' A small but meaningful revision — acknowledging that the Arch belongs to the landscape more than to any single ideology.