Major League Baseball
Major League Baseball is a professional baseball league in North America composed of 30 teams, divided equally between the National League and the American League, with 29 in the United States and 1 in Canada. MLB is one of the major professional sports leagues in the United States and Canada and is considered the premier professional baseball league in the world. Each team plays 162 games per season, with Opening Day held during the last week of March or the first week of April. Six teams in each league then advance to a four-round postseason tournament in October, culminating in the World Series, a best-of-seven championship series between the two league champions first played in 1903. MLB is headquartered in New York City.
Formed in 1876 and 1901, respectively, the NL and AL cemented their cooperation with the National Agreement in 1903, making MLB the oldest major professional sports league in the United States and Canada. They remained legally separate entities until 2000, when they merged into a single organization led by the commissioner of baseball. Baseball's first all-professional team, the Cincinnati Red Stockings, was founded in 1869. The first few decades of professional baseball saw rivalries between leagues, and players often jumped from one team or league to another. These practices were essentially ended by the National Agreement of 1903, in which AL and NL agreed to respect each other's player contracts, including the contentious reserve clause, which bound players to their teams.
The period from about 1900 to 1920 was the dead-ball era, when home runs were rarely hit. Professional baseball was rocked by the Black Sox Scandal, a conspiracy to fix the 1919 World Series. Baseball survived the scandal, albeit with major changes in its governance as the relatively weak National Commission was replaced with a powerful commissioner of baseball with near-unlimited authority over the sport. MLB rose in popularity in the decade following the Black Sox Scandal, and unlike major leagues in other sports, it endured the Great Depression and World War II without any of its teams folding. Shortly after the war, Jackie Robinson broke baseball's color barrier.
Some teams moved to different cities in the 1950s and 1960s. The AL and NL added eight clubs in the 1960s, which started the expansion era: two in 1961, two in 1962, and four in 1969. Player discontent with established labor practices, especially the reserve clause, led to the organization of the Major League Baseball Players Association to collectively bargain with the owners, which in turn led to the introduction of free agency in baseball. Modern stadiums with artificial turf surfaces began to change the game in the 1970s and 1980s. Home runs began to dominate the game during the 1990s. In the mid-2000s, media reports disclosed the use of anabolic steroids among MLB players; a 2006–07 investigation produced the Mitchell Report, which found that many players had used steroids and other performance-enhancing substances, including at least one player from each team.
MLB is the third-wealthiest professional sports league in the world by revenue after the National Football League and the National Basketball Association. Baseball games are broadcast on television, radio, and the internet throughout North America and in several other countries. MLB has the highest total season attendance of any sports league in the world; in, it drew 71.4 million spectators. MLB also oversees Minor League Baseball, which comprises lower-tier teams affiliated with the major league clubs, the MLB Draft League, a hybrid amateur-professional showcase league, and the Arizona Fall League, an off-season showcase league for minor league players. MLB and the World Baseball Softball Confederation jointly manage the international World Baseball Classic tournament. The New York Yankees have the most championships with 27. The reigning champions are the Los Angeles Dodgers, who defeated the Toronto Blue Jays in the 2025 World Series.
History
Founding
In the 1860s, aided by soldiers playing the game in camp during the Civil War, "New York"-style baseball expanded into a national game and spawned baseball's first governing body, the National Association of Base Ball Players. The NABBP existed as an amateur league for 12 years. By 1867, more than 400 clubs were members. Most of the strongest clubs remained those based in the northeastern United States. For professional baseball's founding year, MLB uses the year 1869—when the first professional team, the Cincinnati Red Stockings, was established.A schism developed between professional and amateur ballplayers after the founding of the Cincinnati club. The NABBP split into an amateur organization and a professional organization. The National Association of Professional Base Ball Players, often known as the National Association, was formed in 1871. Its amateur counterpart disappeared after only a few years. The modern Chicago Cubs and Atlanta Braves franchises trace their histories back to the National Association of Professional Base Ball Players in the 1870s.
In 1876, the National League of Professional Base Ball Clubs was established after the NA proved ineffective. The league placed its emphasis on clubs rather than on players. Clubs could now enforce player contracts, preventing players from jumping to higher-paying clubs. Clubs were required to play the full schedule of games instead of forfeiting scheduled games when the club was no longer in the running for the league championship, which happened frequently under the NA. A concerted effort was made to curb gambling on games, which was leaving the validity of results in doubt. The first game in the NL—on Saturday, April 22, 1876 —is often pointed to as the beginning of MLB.
The early years of the NL were tumultuous, with threats from rival leagues and a rebellion by players against the hated "reserve clause", which restricted the free movement of players between clubs. Teams came and went; 1882 was the first season where the league's membership was the same as the preceding season's, and only four franchises survived to see 1900. Competitor leagues formed regularly and also disbanded regularly. The most successful was the American Association, sometimes called the "beer and whiskey league" for its tolerance of the sale of alcoholic beverages to spectators. For several years, the NL and American Association champions met in a postseason championship series—the first attempt at a World Series. The two leagues merged in 1892 as a single 12-team NL, but the NL dropped four teams after the 1899 season. This led to the formation of the American League in 1901 under president Ban Johnson, and the resulting bidding war for players led to widespread contract-breaking and legal disputes.
The war between the AL and NL caused shock waves throughout the baseball world. At a meeting at the Leland Hotel in Chicago in 1901, the other baseball leagues negotiated a plan to maintain their independence. A new National Association was formed to oversee these minor leagues.
After 1902, the NL, AL, and NA signed a new National Agreement which tied independent contracts to the reserve-clause contracts. The agreement also set up a formal classification system for minor leagues, the forerunner of today's system that was refined by Branch Rickey.
Other recognized leagues
Several other early defunct baseball leagues are considered major leagues, and their statistics and records are included with those of the two modern major leagues. In 1969, the Special Baseball Records Committee of Major League Baseball officially recognized six major leagues: the National League, American League, American Association, Union Association, Players' League, and Federal League. The status of the National Association as a major league has been a point of dispute among baseball researchers; while its statistics are not recognized by Major League Baseball, its statistics are included with those of other major leagues by some baseball reference websites, such as Retrosheet. Some researchers, including Nate Silver, dispute the major-league status of the Union Association by pointing out that franchises came and went and that the St. Louis club was deliberately "stacked"; the St. Louis club was owned by the league's president and it was the only club that was close to major-league caliber.In December 2020, Major League Baseball announced its recognition of seven leagues within Negro league baseball as major leagues: the first and second Negro National Leagues, the Eastern Colored League, the American Negro League, the East–West League, the Negro Southern League, and the Negro American League. In 2021, baseball reference website Baseball-Reference.com began to include statistics from those seven leagues into their major-league statistics. In May 2024, Major League Baseball announced that it was "absorbing the available Negro Leagues numbers into the official historical record."
Dead-ball era
The period between 1900 and 1919 is commonly referred to as the "dead-ball era". Games of this era tended to be low-scoring and were often dominated by pitchers, such as Walter Johnson, Cy Young, Christy Mathewson, Mordecai Brown, and Grover Cleveland Alexander. The term also accurately describes the condition of the baseball itself. The baseball used American rather than the modern Australian wool yarn and was not wound as tightly, affecting the distance that it would travel. More significantly, balls were kept in play until they were mangled, soft and sometimes lopsided. During this era, a baseball cost $3,, and owners were reluctant to purchase new balls. Fans were expected to throw back fouls and home runs. Baseballs also became stained with tobacco juice, grass, and mud, and sometimes the juice of licorice, which some players would chew for the purpose of discoloring the ball.Also, pitchers could manipulate the ball through the use of the spitball. Additionally, many ballparks had large dimensions, such as the West Side Grounds of the Chicago Cubs, which was to the center field fence, and the Huntington Avenue Grounds of the Boston Red Sox, which was to the center field fence, thus home runs were rare, and "small ball" tactics such as singles, bunts, stolen bases, and the hit-and-run play dominated the strategies of the time. Hitting methods like the Baltimore chop were used to increase the number of infield singles. On a successful Baltimore chop, the batter hits the ball forcefully into the ground, causing it to bounce so high that the batter reaches first base before the ball can be fielded and thrown to the first baseman.
The adoption of the foul strike rule—in the NL in 1901, in the AL two years later—quickly sent baseball from a high-scoring game to one where scoring runs became a struggle. Before this rule, foul balls were not counted as strikes: a batter could foul off any number of pitches with no strikes counted against him; this gave an enormous advantage to the batter.
After the 1919 World Series between the Chicago White Sox and Cincinnati Reds, baseball was rocked by allegations of a game-fixing scheme known as the Black Sox Scandal. Eight players—"Shoeless" Joe Jackson, Eddie Cicotte, Claude "Lefty" Williams, George "Buck" Weaver, Arnold "Chick" Gandil, Fred McMullin, Charles "Swede" Risberg, and Oscar "Happy" Felsch—intentionally lost the World Series in exchange for a ring worth $100,000. Despite being acquitted, all were permanently banned from MLB.