American college and professional sports have gained enormous popularity since the "Sports Golden Age" of the 1920s. As American technology advanced, so did American sport. Its popularity led to its commercialization. Huge stadia were built, athletes were able to command enormous salaries; media interest and coverage increased which led to the emergence of sports heroes. American sport was a "whites only" institution until 1947 when Jackie Robinson broke the color barrier in Major League Baseball. The cultural and social variables which impact upon, shape the lives of, and establish the values of African American males are complex. Much of African American culture is rooted in its historical and contemporary reaction to white racism and discrimination. The economic and social conditions of the lower class shape their socialization, making it distinct from other economic and social groups. Social class also impacts on the quality of education one receives and the development of educational values, which significantly impacts on educational achievement.