Final answer:
The existence of the "Negro leagues" in professional baseball during the 1930s and 1940s is an example of racial segregation in sports.
Step-by-step explanation:
The existence of the "Negro leagues" in professional baseball in the United States during the 1930s and 1940s is an example of racial segregation in sports. During this time period, African American players were excluded from playing in the major leagues due to racial discrimination. As a result, separate baseball leagues were formed for African American players, such as the Negro National League, to provide them with opportunities to showcase their talent.