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. 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. 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. 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 Cuban-born (and black) Minnie Miñoso, became the first Hispanic All-Stars.
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. Integration proceeded slowly: by 1953, only six of the sixteen major league teams had a black player on the roster. 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. 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. The majors' final all-white bastion, the Boston Red Sox, added a black player in 1959. With the integration of the majors drying up the available pool of players, the last Negro league folded the following year. 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.
Rules and gameplay
A game is played between two teams, each composed of nine players, that take turns playing offense (batting or hitting) and defense (fielding or pitching). A pair of turns, one at bat and one in the field, by each team constitutes an inning; there are nine innings in a game. One team—customarily the visiting team—bats in the top, or first half, of every inning; the other team—customarily the home team—bats in the bottom, or second half, of every inning. The goal of a game is to score more points (runs) than the other team. The players on the team at bat attempt to score runs by circling, or completing a tour of, the four bases set at the corners of the square-shaped baseball diamond. A player bats at home plate and must proceed counterclockwise to first base, second base, third base, and back home in order to score a run. The team in the field attempts both to prevent runs from scoring and to record outs, which remove opposing players from offensive action until their turn in their team's batting order comes up again. When three outs are recorded, the teams switch roles for the next half-inning. If the score of the game is tied after nine innings, extra innings are played to resolve the contest. Children's games are often scheduled