March 10, 1804

Three Flags Day

The United States assumes authority over Upper Louisiana at St. Louis

For just under 24 hours St. Louis was ceremonially French again — and the same officer, Amos Stoddard, received Upper Louisiana for France and then handed it to himself for the United States.

10 March 1804: the second half of a two-day handover

Before noon on 10 March 1804, residents and officials reassembled at the government mansion in St. Louis for the second half of a two-day transfer ceremony. The day before, a cannon had saluted the French flag as Spain handed the territory to France.

U.S. Army Captain Amos Stoddard signed the transfer papers and addressed the assembled residents. The French flag came down; the United States flag went up.

Why one man stood on both sides

France had sent no separate representative for the transfer, so Stoddard acted for both France and the United States. There was no French official handing the territory across to him.

The oddity had a cause: France had retroceded Louisiana from Spain and sold it to the United States in 1803, but Spanish officials still administered St. Louis. A local two-stage handover was therefore required — Spain to France on 9 March, France to the United States on 10 March.

What the flag change did

By noon the American flag flew over the government house and Stoddard exercised United States authority over Upper Louisiana, ending Spanish colonial administration in St. Louis. One account records that after an all-night celebration under the tricolor, the exhausted crowd's requested three cheers for the American flag were not hearty.

The ceremony transferred sovereignty and governmental possession over Upper Louisiana; it was not the signing of the purchase treaty, which had taken place in Paris on 30 April 1803. Calling it uncomplicated “ownership” erases unresolved boundaries and the sovereignty and land rights of Indigenous nations.

Sources

Researched 23 Aug 2026 6 sources 3 audit passes

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

What the sources leave uncertain

The event spans March 9–10. March 10 is correct for the France-to-United-States stage; March 9 was the Spain-to-France stage.
Contemporary documents concern the transfer of sovereignty and governmental possession over Upper Louisiana. Calling it uncomplicated 'ownership' erases unresolved boundaries and the sovereignty and land rights of Indigenous nations.