National Scrabble Day (13 April)

Tony Cooper on a.u.e. beat me to this.
It's the birthday of Alfred Mosher Butts (1899-1993), an American architect who loved word games, and figured out how to make one that was intensely competitive -- give points for letters!
"Scrabble" (the name) was trademarked by the Hasbro company in 1948.
The letter values and numbers of tiles for each letter were based on frequencies on the front page of the New York Times.
BUT there were only four S's (less than you would expect), since "to have more would weaken the game by allowing too many plural noun and third-person verb forms." (Crystal)