Claim: Jackie Robinson's uniform number was 42.

Jackie Robinson Day is a traditional event which occurs annually in Major League Baseball , commemorating and honoring the day Jackie Robinson made his major league debut . April 15 was Opening Day in 1947 , Robinson 's first season in the Major Leagues . Initiated for the first time on April 15 , 2004 , Jackie Robinson Day is celebrated each year on that day . The festivity is a result of Robinson 's memorable career , best known for becoming the first black major league baseball player of the modern era in 1947 . His debut with the Brooklyn Dodgers -LRB- today known as the Los Angeles Dodgers -RRB- ended approximately 80 years of baseball segregation , also known as the baseball color line , or color barrier . He also was inducted into the Baseball Hall of Fame in 1962 , remembered for his services with the number 42 jersey .   The gala is celebrated at varied ballparks by Major League team players . On that one day , all players , coaches , and managers on both teams , and the umpires , wear # 42 on their jerseys .   Shea Stadium was one of the prominent venues hosting the event , having commemorated the retirement of Robinson 's number 42 jersey in . Bob DuPuy , the President and Chief Operating Officer of Major League Baseball , described Jackie Robinson Day as a significance `` not only for baseball , but for our country in general . ''