It’s Jackie Robinson Day in the United States on April 15th. Robinson broke the baseball color line when he started at first base for the Brooklyn Dodgers on this day in 1947. When the Dodgers signed Robinson, they heralded the end of racial segregation in professional baseball that had relegated black players to the Negro leagues since the 1880s.
In 1997, Major League Baseball retired Robinson’s uniform number 42 across all major league teams; he was the first professional athlete in any sport to be so honored. MLB adopted Jackie Robinson Day for the first time on April 15, 2004, on which every player on every team wears No. 42. Read more (Wikipedia).