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ST. LOUIS–April 15 is celebrated annually by Major League Baseball, marking the day in 1947 Jackie Robinson made his big league debut, breaking baseball’s color barrier. Baseball has made it a two-day celebration, allowing teams who may not be playing on one day to honor Robinson on the other.

For the Cardinals, the day is a travel day to Philadelphia for a weekend series against the Phillies starting Friday, when both teams will wear Robinson’s number 42, which has otherwise been retired.

On Thursday, MLB took to social media, sharing “Thank You” notes from players around the league expressing what Robinson meant to them, including Cardinals pitcher Jack Flaherty.

“We have an opportunity to play baseball because of all the hate you went through to play this game,” Flaherty wrote. “For that I am forever grateful and for that I will never take this game for granted knowing how lucky that I am to be out there.”

Former Cardinals outfielder Tommy Pham, now with San Diego, wrote “Wearing 42 today is a step in the right direction. It signifies equality and it signifies meaning as a Black man in this game being able to live the childhood dream. To see where we cam from and how far we’ve come since, it’s truly a blessing.”