|Founded||January 28, 1901|
|President||Frank Robinson (honorary)  |
|No. of teams||15|
|Countries||United States (14 teams)|
Canada (1 team)
|Boston Red Sox (14th)|
|Most titles||New York Yankees (40)|
The American League of Professional Baseball Clubs, or simply the American League (AL), is one of two leagues that make up Major League Baseball (MLB) in the United States and Canada. It developed from the Western League, a minor league based in the Great Lakes states, which eventually aspired to major league status. It is sometimes called the Junior Circuit because it claimed Major League status for the 1901 season, 25 years after the formation of the National League (the "Senior Circuit").
At the end of every season, the American League champion plays in the World Series against the National League champion; two seasons did not end in playing a World Series (1904, when the National League champion New York Giants refused to play their AL counterpart, and 1994, when a players' strike prevented the Series). Through 2018, American League teams have won 66 of the 114 World Series played since 1903, with 27 of those coming from the New York Yankees alone. The New York Yankees have won 40 American League titles, the most in the league's history, followed by the Philadelphia/Kansas City/Oakland Athletics (15) and the Boston Red Sox (14).
Originally a minor league known as the Western League which existed 1885 to 1899, with teams in mostly Great Lakes states, the newly organized Western League later developed into a rival major league after the previous American Association (1882–1891) disbanded after ten seasons as a competitor to the older National League of Professional Baseball Clubs (usually known as the National League) which was founded in 1876. In its early history of the late 1880s, the minor Western League struggled until 1894, when Ban Johnson (1864–1931) became the president of the league. Johnson led the Western League into elevation as claiming major league status and soon became the president of the newly renamed American League of Professional Baseball Clubs (also simply called the American League) in 1901. George Herman ("Babe") Ruth (1895–1948), noted as one of the most prolific hitters in Major League Baseball history, spent the majority of his career in the American League with the Boston Red Sox and the New York Yankees (plus his first year with his hometown team, the Baltimore Orioles of the minor level International League). The American League has one notable difference versus the rival National League, in that in modern times since 1973 it has had the designated hitter rule. Under the rule, a team may use a batter in its lineup who is not in the field defensively, replacing the pitcher in the batting order, compared to the old rule that made it mandatory for the pitcher to bat. In the last two decades, the season schedule has allowed occasional interleague play.
Until the late 1970s, league umpires working behind home plate wore large, balloon-style chest protectors worn outside the shirt or coat, while their brethren in the National League wore chest protectors inside the shirt or coat. In 1977, new umpires (including Steve Palermo) had to wear the inside chest protector, although those on staff wearing the outside protector could continue to do so. Most umpires made the switch to the inside protector, led by Don Denkinger in 1975 and Jim Evans the next year, although several did not, including Bill Haller, Lou DiMuro, George Maloney, and Jerry Neudecker, who became the last MLB umpire to use the outside protector in 1985.
In 1994, the league, along with the National League, reorganized again, into three divisions (East, West, and Central) and added a third round to the playoffs in the form of the American League Division Series, with the best second-place team advancing to the playoffs as a wild-card team, in addition to the three divisional champions. In 1998, the newly franchised Tampa Bay Devil Rays joined the league, and the Arizona Diamondbacks joined the National League: i.e., each league each added a fifteenth team. An odd number of teams per league meant that at least one team in each league would have to be idle on any given day, or alternatively that odd team out would have had to play an interleague game against its counterpart in the other league. The initial plan was to have three five-team divisions per league with inter league play year-round—possibly as many as 30 interleague games per team each year. For various reasons, it soon seemed more practical to have an even number of teams in both leagues. The Milwaukee Brewers agreed to change leagues, moving from the AL Central to the NL Central. At the same time, the Detroit Tigers were moved from the AL East to the AL Central, making room for the Devil Rays in the East. Following the move of the Houston Astros, which had been in the NL for 51 years since beginning as an expansion team in 1962, to the American League in 2013, both leagues now consist of 15 teams, a far cry from their original 8 for the first half-century of the 20th century.
For the first 96 years, American League teams faced their National League counterparts only in exhibition games or in the World Series. Beginning in 1997, interleague games have been played during the regular season and count in the standings. As part of the agreement instituting interleague play, the designated-hitter rule is used only in games where the American League team is the home team.
There were eight charter teams in 1901, the league's first year as a major league, and the next year the original Milwaukee Brewers moved to St. Louis to become the St. Louis Browns. These franchises constituted the league for 52 seasons, until the Browns moved to Baltimore and took up the name Baltimore Orioles. All eight original franchises remain in the American League, although only four remain in the original cities (Detroit, Chicago, Boston, and Cleveland). The eight original teams and their counterparts in the "Classic Eight" were:
- original Baltimore Orioles (went bankrupt and became defunct after 1902 season, not to be confused with the current Baltimore Orioles, see Milwaukee Brewers),  replaced in 1903 by the New York Highlanders (became the New York Yankees in 1913)
- Boston Americans (became the Boston Red Sox in 1908)
- Chicago White Stockings (became the Chicago White Sox in 1904)
- Cleveland Blues  (became the Cleveland Indians in 1915)
- Detroit Tigers (name and locale unchanged from 1894 forward)
- original Milwaukee Brewers (became the St. Louis Browns in 1902 and the new Baltimore Orioles in 1954)
- Philadelphia Athletics (became the Kansas City Athletics in 1955 and the Oakland Athletics in 1968)
- original Washington Senators (became the Minnesota Twins in 1961) 
- 1902: Original Milwaukee Brewers moved to St. Louis, renamed St. Louis Browns
- 1902: Cleveland Bluebirds/Blues players attempted to adopt the nickname Cleveland Bronchos, which failed to catch on
- 1903: New York Highlanders Original Baltimore Orioles moved to New York; dubbed "Highlanders" by press after their field, Hilltop Park, and "Yanks" as a shorter form of "Americans"
- 1903: Chicago White Stockings officially renamed Chicago White Sox
- 1903: Cleveland Blues/Bronchos renamed Cleveland Naps via newspaper poll, after star Nap Lajoie
- 1905: Washington Senators renamed Washington Nationals; Senators name continued to be used by media
- 1908: Boston Americans (informal nickname) formally named Boston Red Sox
- 1913: New York Highlanders nickname dropped in favor of already-established alternative, New York Yankees
- 1915: Cleveland Naps renamed Cleveland Indians
- 1954: St. Louis Browns move to Baltimore, renamed Baltimore Orioles
- 1955: Philadelphia Athletics move to Kansas City
- 1957: Washington Nationals/Senators formally renamed Washington Senators
- 1961: Washington Senators move to Minneapolis-St. Paul, renamed Minnesota Twins
- 1961: Los Angeles Angels and new Washington Senators enfranchised.
- 1965: Los Angeles Angels renamed California Angels in late-season on September 2, 1965. For the following season, the Angels moved within the Los Angeles metropolitan area from the city of Los Angeles to the Orange County suburb of Anaheim.
- 1968: Kansas City Athletics move to Oakland
- 1969: Kansas City Royals and Seattle Pilots enfranchised.
- 1970: Seattle Pilots move to Milwaukee, renamed Milwaukee Brewers. (Four years earlier, in 1966, the National League's Milwaukee Braves had moved to Atlanta.)
- 1972: Washington Senators move to Dallas-Ft. Worth (Arlington), renamed Texas Rangers
- 1973: Oakland Athletics officially renamed Oakland A's
- 1977: Seattle Mariners and Toronto Blue Jays enfranchised
- 1980: Oakland A's officially renamed Oakland Athletics
- 1997: California Angels renamed Anaheim Angels. The change came more than 30 years after the team's move to Anaheim.
- 1998: Tampa Bay Devil Rays, representing Tampa-St. Petersburg, enfranchised
- 1998: Milwaukee Brewers transfer from the American League to the National League. (See above.)
- 2005: Anaheim Angels renamed Los Angeles Angels of Anaheim
- 2008: Tampa Bay Devil Rays renamed Tampa Bay Rays
- 2013: Houston Astros transfer from the National League Central to the American League West.
- 2016: Los Angeles Angels of Anaheim slowly phase out official use of "of Anaheim" sub-title in favor of just Los Angeles Angels
- Baltimore Orioles enfranchised 1901 as the Milwaukee Brewers, moved to St. Louis (1902) and to Baltimore (1954)
- Boston Red Sox enfranchised 1901, nicknamed the Americans  (adopted name Red Sox in 1908)
- New York Yankees enfranchised 1901 as Baltimore Orioles, moved to New York (1903) and nicknamed the Highlanders  (officially adopted alternate nickname Yanks/Yankees in 1913) 
- Tampa Bay Rays enfranchised 1998 as the Tampa Bay Devil Rays (team name changed in 2008)
- Toronto Blue Jays enfranchised 1977 
- Chicago White Sox enfranchised 1894 as the Sioux City Cornhuskers, moved to St. Paul (1895) and to Chicago (1900)
- Cleveland Indians enfranchised 1894 as the Grand Rapids Rustlers, moved to Cleveland (1900)
- Detroit Tigers enfranchised 1894
- Kansas City Royals enfranchised 1969
- Minnesota Twins enfranchised 1894 as the Kansas City Blues, moved to Washington (1901), and to Minneapolis-St. Paul (1961)
- Houston Astros enfranchised 1962 in National League as the Houston Colt .45s (team changed name to Astros in 1965), transferred to American League (2013)
- Los Angeles Angels enfranchised 1961 as the Los Angeles Angels, then as the California Angels after moving to Anaheim (1966), then the Anaheim Angels (1997), then the Los Angeles Angels of Anaheim (2005). This last remains the legal name of the franchise, but in actual practice the team is known as the Los Angeles Angels.
- Oakland Athletics enfranchised 1901 [a] in Philadelphia, moved to Kansas City (1955) and to Oakland (1968)
- Seattle Mariners enfranchised 1977
- Texas Rangers enfranchised 1961 as the Washington Senators, moved to Arlington, Texas (1972)
Following the 1999 season, the American and National Leagues were merged with Major League Baseball, and the leagues ceased to exist as business entities. The position of the American League President and National League President became honorary.
|Member of the Baseball Hall of Fame|
- American League portal
- List of American League pennant winners
- American League Championship Series (ALCS)
- American League Division Series (ALDS)
- List of American League Wild Card winners
- Major League Baseball
- National League
- World Series
- See commentary on Western League page. The Indianapolis and Minneapolis teams were replaced by teams in Baltimore and Philadelphia in 1901, but it is unclear and disputed as to which team went where.
- "Frank Robinson named Senior Advisor and Honorary A.L. President" (Press release). Major League Baseball Advanced Media. February 2, 2015. Retrieved March 9, 2016.
- "Hall of Famer Robinson to become senior adviser to MLB commish". Fox Sports. Associated Press. February 2, 2015. Retrieved March 9, 2016.
- "Bankrupt Orioles". Baseball-Reference. Archived from the original on July 23, 2014. Retrieved July 20, 2014.
- Officially "Bluebirds", a form seldom used
- "American League". Chicago Tribune. Retrieved August 25, 2013.
- To distinguish them from Boston's National League team, then called the Red Stockings or the Nationals
- after their home, Hilltop Park
- Sources recently have dissociated the 1902–1903 Baltimore Orioles from the Highlanders/Yankees. Sports Reference.com Archived July 23, 2014, at the Wayback Machine. and sources cited on that page. Retrieved July 23, 2014.
- Edgarf. "Baltimore Orioles History – American League East". MLB Baseball Betting. Retrieved August 25, 2013.
- The National League Story, Lee Allen, Putnam, 1961.
- The American League Story, Lee Allen, Putnam, 1962.
- The Baseball Encyclopedia, published by MacMillan, 1968 and later.