DS Update: Grand Centennial Exposition?

OK, so there's this planter of flowers in Exposition Park labeled as the Grand Centennial Exposition but what is that? The marker indicates it marks a "Century of Progress" since the founding of Disney Springs but the terms "century" and "centennial" infer 100 years ago but then the marker indicates 1950 which would be 72 years ago. I realize this is made-up back-story nonsense but shouldn't the made-up dates be correct?

And really, the Great Seal of the city of Disney Springs doesn't even have a date on it! Not really sure what this is all about!