Museum of Westward Expansion, Saint Louis

The Museum of Westward Expansion was a history museum located underground beneath the Gateway Arch in St. Louis, Missouri, that explored the United States' expansion into the western frontier during the 19th century.

Opened in 1976 as part of the Jefferson National Expansion Memorial, the museum examined the people, events, and technologies that shaped westward migration following the Louisiana Purchase. In February 2015, the original museum closed to undergo a massive transformation. On July 3, 2018, following a $380 million renovation of the national park grounds and visitor center, the space was completely redesigned, expanded, and reopened as the Museum at the Gateway Arch. The original museum featured exhibits on early explorers, pioneers, Native American nations, fur traders, soldiers, and settlers who traveled across the continent. Its displays included historic artifacts, life-size recreations, maps, covered wagons, firearms, and tools illustrating daily life on the frontier. The redesigned museum significantly expanded this historical narrative. It now presents multiple, diverse perspectives on westward expansion, explicitly integrating the lived experiences and histories of Indigenous peoples, enslaved individuals, and immigrants affected by the nation's growth.

Today, the legacy of the Museum of Westward Expansion continues through the Museum at the Gateway Arch. Visitors can explore six updated, universally accessible story galleries using original artifacts, multimedia presentations, and immersive displays. Together with the Gateway Arch and the surrounding Gateway Arch National Park, the museum provides critical historical context for one of the most significant periods of American history, encouraging visitors to examine both the opportunities and the complex consequences of westward expansion.