In 1947,Jackie Robinson bacame the first player in the modern major leagues, bringing an end to baseball’s exclusion of blacks. Robinson’s success as a player opened the door for other blacks to play professional baseball on previously all white teams. In 1954 only 7 percent of all major league players were black. By 1980 the number of black players on major league rosters had reached a high of 22 percent. Other key changes ocurred in 1958, when the Brooklyn Dodgers moved to Los Angeles, and the New York Giants moved to San Francisco, expanding baseball’s market right across the United States.

Professional baseball had become so popular that many cities began requesting permission to creat new clubs. During the 1960s, the National League and American League each added four new teams, creating a total of 12 teams in each league. Beginning in 1969, each league was divided into separate East and West divisions, the winners of which played each other in the league playoffs. Expansion proved successful, as millions of fans attended major league games across the country each year. Television networks also purchased the rights to broadcast major league games, which added to baseball’s growing popularity.