The Kansas City Monarchs were the longest-running franchise in the history of baseball's Negro leagues. Operating in Kansas City, Missouri, and owned by J. L. Wilkinson, they were charter members of the Negro National League from 1920 to 1930. J. L. Wilkinson was the first Caucasian owner at the time of the establishment of the team. In 1930, the Monarchs became the first professional baseball team to use a portable lighting system which was transported from game to game in trucks to play games at night, five years before any major league team did. The Monarchs won ten league championships before integration, and triumphed in the first Negro League World Series in 1924. The Monarchs had only one season in which they did not have a winning record. The team produced more major league players than any other Negro league franchise. It was disbanded in 1965.

Jack Roosevelt Robinson (January 31, 1919 – October 24, 1972) was an American professional baseball player who became the first African American to play in Major League Baseball (MLB) in the modern era. Robinson broke the baseball color line when he started at first base for the Brooklyn Dodgers on April 15, 1947. When the Dodgers signed Robinson, it heralded the end of racial segregation in professional baseball that had relegated black players to the Negro leagues since the 1880s. Robinson was inducted into the Baseball Hall of Fame in 1962.During his 10-year MLB career, Robinson won the inaugural Rookie of the Year Award in 1947, was an All-Star for six consecutive seasons from 1949 through 1954, and won the National League Most Valuable Player Award in 1949—the first black player so honored. Robinson played in six World Series and contributed to the Dodgers' 1955 World Series championship.

In 1997, MLB retired his uniform number 42 across all major league teams; he was the first professional athlete in any sport to be so honored. MLB also adopted a new annual tradition, "Jackie Robinson Day", for the first time on April 15, 2004, on which every player on every team wears No. 42.

Robinson's character, his use of nonviolence, and his talent challenged the traditional basis of segregation that had then marked many other aspects of American life. He influenced the culture of and contributed significantly to the civil rights movement. Robinson also was the first black television analyst in MLB and the first black vice president of a major American corporation, Chock full o'Nuts. In the 1960s, he helped establish the Freedom National Bank, an African-American-owned financial institution based in Harlem, New York. After his death in 1972, Robinson was posthumously awarded the Congressional Gold Medal and Presidential Medal of Freedom in recognition of his achievements on and off the field.