The number 21 on MLB jerseys is a tribute to Roberto Clemente, a legendary Puerto Rican baseball player and humanitarian. MLB celebrates Roberto Clemente Day every September 15, during which all players, managers, coaches, and umpires wear a white "21" patch on their jerseys. Additionally, players of Puerto Rican heritage, past winners, and nominees of the Roberto Clemente Award may wear the number 21 on their uniforms to honor his legacy. Clemente was known not only for his outstanding baseball career but also for his humanitarian work. He died in 1972 while delivering earthquake relief supplies, and his number 21 was retired by the Pittsburgh Pirates. This tribute recognizes his impact on the sport and community.
