Three Flags Day commemorates a relatively obscure moment in American history.

From the Atlas Obscura website …

Although the Louisiana Purchase technically went through on April 30, 1803, transferring hundreds of millions of acres of land is no small feat. It took months for the requisite arrangements to be made. Throughout the summer and fall of 1803, Congress signed papers, and money changed hands. That winter, there was an official Americanizing ceremony in New Orleans, which served as the territory’s capital. 

A depiction of the signing of the Louisiana Treaty near New Orleans.

 

But because it was winter in the 1800s, the many territory residents north of New Orleans didn’t get word of that switch until much later. So in March of 1804, it was decided that there should be another official ceremony, in St. Louis.

 

But there was a small problem: St. Louis was one of the cities the Spanish hadn’t gotten around to giving up. Authorities soon realized that, in order to actualize the territory’s new identity, “two treaties must be put into effect at one time,” writes historian Walter Barlow Stevens in St. Louis, The Fourth City. First, the land had to be be transferred from Spain to France. Then, it had to be be transferred again, from France to the United States.

Keeping all that in mind, Mayor Anthony, at Tuesday’s meeting of the Riverdale City Council, issued a mayoral proclamation making the period from noon on March 9 through noon on March 10, Three Flags Day in Riverdale.