KANSAS CITY, MISSOURI — Brooklyn Dodgers president and general manager Branch Rickey signed Kansas City Monarchs infielder Jackie Robinson on Oct. 23, 1945, a move that would ultimately make Robinson the first Black player in Major League Baseball. The signing came after Rickey's initial efforts to recruit a different Negro Leagues player were blocked by a team owner who refused to release her star.

Robinson was not Rickey's first choice when the Dodgers executive set out to sign a player from the Negro Leagues. Rickey had preferred Monte Irvin, an athlete who had recently returned from military service in World War II. But Effa Manley, owner of the Newark Eagles, refused to allow Rickey to sign Irvin. That refusal led the Dodgers' top executive to turn his attention to Robinson instead.

Jackie Roosevelt Robinson had joined the Kansas City Monarchs following his own stint in the military. Before entering professional baseball, Robinson had been an All-America football player at UCLA, demonstrating versatility across multiple sports. At the time he signed with the Dodgers organization in October 1945, Robinson was about to marry Rachel Robinson.

Robinson's eventual debut in Major League Baseball preceded several key moments in the broader history of civil rights in the United States. He appeared in the major leagues years before the Supreme Court issued its 1954 Brown v. Board of Education decision and before Rosa Parks refused to give up her seat on a Montgomery, Alabama, bus in December 1955. Martin Luther King Jr. was a sophomore at Morehouse College when Robinson signed his contract with the Brooklyn Dodgers in 1945.

The Negro Leagues Baseball Museum has stated that Robinson's breaking of baseball's color barrier marked the beginning of the Civil Rights Movement in the United States. The museum's assertion places the Oct. 23, 1945, signing and Robinson's subsequent major league career at the forefront of a period of social change that would reshape the country over the following two decades.