April 15, a date commemorating and honoring the day Jackie Robinson made his major league debut.
In order for the celebration of the day, there is an interesting phenomena in the following picture. Could you see that? Ha, the picther, the batter, the runner, and the defender, all numbers on the uniforms are the same - No. 42, an universal retired number in MLB, except for, of course, Mariano Rivera, the closer of NYY. On the day in 2009, for the first time, all uniformed personel (players, managers and coaches) are being asked to wear #42 for the day.