On December 20, 1803, William C.C. Claiborne, Governor of the Mississippi Territory and one of the commissioners appointed to take possession of Louisiana from France, participated in the ceremonial exchange of the territory from Spain to France to the United States. Claiborne issued this proclamation in three languages (English, French, and Spanish) to inform the residents of the territory that they would soon become citizens of the United States, and that in the mean time they could enjoy the freedoms and liberty under the protection of the U.S. Constitution.
Proclamation of William C.C. Claiborne, 12/20/1803, HR 8A-D1, Records of the U.S. House of Representatives (ARC 593571)