Baseball entered a new era in 1901, however, when the American League started its first season. The American League was founded by Ban Johnson, president of the Western League, a successful minor league organization that he renamed the American League. In 1903 the National League agreed to recognize the American League, and the championship teams from each league met in the first World Series. Major League Baseball enjoyed widespread popularity during the early 1900s. Attendance at games swelled, and the World Series became one of the leading annual events in sport. Outstanding players such as Cy Young, Christy Mathewson, and Ty Cobb emerged as national stars.

Owners responded to the prosperity by building larger, more modern ballparks. Baseball’s success also brought difficulties. Baseball faced its largest challenge following the 1919 World Series, in which the Cincinnati Reds defeated the Chicago White Sox. The following year, seven Chicago players were banned from baseball for internationally losing the series in exchange for bribes from professional gamblers. An eighth Chicago player was banned because he know of the plan but did not report it. This scandal severely damaged baseball’s public image. Baseball reputation recovered, however, under the leadership of its first commissioner, a federal judge named Kenesaw Mountain Landis.