How is racial integration connected to professional sports?

Answer 1

The 1947-1948 baseball season opened with a new Brooklyn Dodger at second base: Jackie Robinson, the first African American in the major leagues. For the first time in the 20th century, professional baseball--the national pastime--was integrated.

Since the late 19th century, pro-baseball and other professional sports had barred black players. The only venues open to black professional athletes were the Harlem Globetrotters, the "clown princes" of Basketball, and segregated black teams.

In 1946, when the football Rams moved from Cleveland to Los Angeles, they signed two black football stars from UCLA, Kenny Washington and Woody Strode. In 1950, the Boston Celtics of the National Basketball League signed Chuck Cooper, and the New York Knicks signed Nat "Sweetwater" Clifton. In the wake of the defeat of the Nazis and their abhorrent racial policies, American professional sports were integrated.

- http://www.digitalhistory.uh.edu/disp_textbook.cfm?smtID=2&psid=3424