Gateway Arch National Park in St. Louis occupies a historic riverfront linked to the Louisiana Purchase, the launch of the Lewis and Clark Expedition, the transfer of Upper Louisiana, and the Dred Scott case through the nearby Old Courthouse. Created in 1935 as Jefferson National Expansion Memorial and redesignated a national park in 2018, it combines national themes of expansion, ambition, and conflict in a compact urban setting. Its centerpiece, the 630-foot Gateway Arch, was designed by Eero Saarinen and completed in 1965 after decades of planning, demolition, delay, and construction, becoming the tallest monument in the United States and the city’s defining symbol.