Rise of Ruth and racial integration

Compared with the present, professional baseball in the early twentieth century was lower scoring and pitchers, the likes of Walter Johnson and Christy Mathewson, were more dominant. The "inside game", which demanded that players "scratch for runs", was played much more aggressively than it is today: the brilliant and often violent Ty Cobb epitomized this style.^[36] The so-called dead-ball era ended in the early 1920s with several changes in rule and circumstance that were advantageous to hitters. Strict new regulations governing the ball's size, shape and composition, coupled with superior materials available after World War I, resulted in a ball that traveled farther when hit. The construction of additional seating to accommodate the rising popularity of the game often had the effect of bringing the outfield fences closer in, making home runs more common.^[37] The rise of the legendary player Babe Ruth, the first great power hitter of the new era, helped permanently alter the nature of the game. The club with which Ruth set most of his slugging records, the New York Yankees, built a reputation as the majors' premier team.^[38] In the late 1920s and early 1930s, St. Louis Cardinals general manager Branch Rickey invested in several minor league clubs and developed the first modern "farm system".^[39] A new Negro National League was organized in 1933; four years later, it was joined by the Negro American League. The first elections to the Baseball Hall of Fame took place in 1936. In 1939 Little League Baseball was founded in Pennsylvania. By the late 1940s, it was the organizing body for children's baseball leagues across the United States.

Jackie Robinson in 1945, with the era's Kansas City Royals, a barnstorming squad associated with the Negro American League's Kansas City Monarchs

With America's entry into World War II, many professional players had left to serve in the armed forces. A large number of minor league teams disbanded as a result and the major league game seemed under threat as well. Chicago Cubs owner Philip K. Wrigley led the formation of a new professional league with women players to help keep the game in the public eye — the All-American Girls Professional Baseball League existed from 1943 to 1954.^[40] The inaugural College World Series was held in 1947, and the Babe Ruth League youth program was founded. This program soon became another important organizing body for children's baseball. The first crack in the unwritten agreement barring blacks from white-controlled professional ball occurred the previous year: Jackie Robinson was signed by the National League's Brooklyn Dodgers—where Branch Rickey had become general manager—and began playing for their minor league team in Montreal.^[41] In 1947, Robinson broke the major leagues' color barrier when he debuted with the Dodgers. Larry Doby debuted with the American League's Cleveland Indians the same year.^[42] Latin American players, largely overlooked before, also started entering the majors in greater numbers. In 1951, two Chicago White Sox, Venezuelan-born Chico Carrasquel and black Cuban-born Minnie Miñoso, became the first Hispanic All-Stars.^[43][44]
Facing competition as varied as television and football, baseball attendance at all levels declined. While the majors rebounded by the mid-1950s, the minor leagues were gutted and hundreds of semipro and amateur teams dissolved.^[45][46] Integration proceeded slowly: by 1953, only six of the sixteen major league teams had a black player on the roster.^[43] That year, the Major League Baseball Players Association was founded. It was the first professional baseball union to survive more than briefly, but it remained largely ineffective for years.^[47] No major league team had been located west of St. Louis until 1958, when the Brooklyn Dodgers and New York Giants relocated to Los Angeles and San Francisco, respectively.^[48] The majors' final all-white bastion, the Boston Red Sox, added a black player in 1959.^[43] With the integration of the majors drying up the available pool of players, the last Negro league folded the following year.^[49] In 1961, the American League reached the West Coast with the Los Angeles Angels expansion team, and the major league season was extended from 154 games to 162. This coincidentally helped Roger Maris break Babe Ruth's long-standing single-season home run record, one of the most celebrated marks in baseball.^[50] Along with the Angels, three other new franchises were launched during 1961–62. With this, the first major league expansion in sixty years, each league now had ten teams.

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