Major League Baseball (MLB) players are wearing the number 21 to honor Roberto Clemente on Roberto Clemente Day, celebrated annually on September 15. This tribute recognizes Clemente's remarkable career as a star player with the Pittsburgh Pirates, his humanitarian efforts, and his lasting legacy. All players, managers, coaches, and umpires wear a white "21" patch on their uniforms as a sign of respect. Additionally, players of Puerto Rican heritage, past recipients, and nominees of the Roberto Clemente Award have the option to wear the number 21 jersey. Clemente Day also coincides with the start of National Hispanic Heritage Month, celebrating Clemente's impact both on and off the field. The Pittsburgh Pirates, Clemente's team throughout his career, often wear No. 21 across their roster during these celebrations.