why do mlb players have 21 on their jerseys

MLB players wear the number 21 on their jerseys primarily to honor Roberto Clemente, a legendary Hall of Fame player known for his outstanding career and humanitarian work. The number 21 represents Clemente's legacy and the contributions of Latin American players to baseball. This tradition is especially observed on Roberto Clemente Day (September 15) and during National Hispanic Heritage Month. Additionally, players of Puerto Rican heritage, past winners, and nominees of the Roberto Clemente Award often wear the number 21 as a tribute to Clemente’s impact on and off the field. All MLB players, managers, and coaches also wear a "21" patch on their uniforms on Roberto Clemente Day to commemorate his legacy.