Question: The American League adopted the designated hitter rule in 1973 prior to being dissolved as an entity and merged to form which organization?

Context paragraphs:
George Maloney: George Patrick Maloney (February 28, 1928 - July 29, 2003) was a professional baseball umpire who worked in the American League from 1969 to 1983, wearing uniform number 28 when the American League adopted them for umpires in 1980.  Maloney umpired 2,159 major league games in his 15-year career.  He umpired in one World Series (1975), three All-Star Games (1974, 1979 and 1983, becoming the last AL umpire to wear the outside balloon protector favored by AL umpires in All-Star competition), three American League Championship Series (1973, 1976 and 1980), and the 1981 American League Division Series.

Designated hitter: In baseball, the designated hitter rule is the common name for Major League Baseball Rule 5.11, adopted by the American League in 1973.  The rule allows teams to have one player, known as the designated hitter (abbreviated DH), to bat in place of the pitcher.  Since 1973, most collegiate, amateur, and professional leagues have adopted the rule or some variant.  MLB's National League and Nippon Professional Baseball's Central League are the most prominent professional leagues that do not use a designated hitter.

History of the American League: The History of the American League, officially known as the American League of Professional Baseball Clubs and often abbreviated AL, stretched back into the late-19th century.  Prior to 2000, when the AL and NL were dissolved as separate entities and merged into the organization called Major League Baseball, the American League was one of the two leagues that made up major league baseball.  Originally a minor league known as the Western League, the league later developed into a major league after the American Association disbanded.  In its early history, the Western League struggled until 1894, when Ban Johnson became the president of the league.  Johnson led the Western League into major league status and soon became the president of the newly renamed American League.  The American League has one notable difference over the National League, and that is the designated hitter rule.  Under the rule, a team may use a batter in their lineup who is not in the field defensively, compared to the old rule that made it mandatory for the pitcher to hit.

Willie Horton (baseball): Willie Wattison Horton (born October 18, 1942) is a former left fielder and designated hitter in Major League Baseball who played for six American League teams, primarily the Detroit Tigers.  He hit 20 or more home runs seven times, and his 325 career home runs ranked sixth among AL right-handed hitters when he retired.  He enjoyed his best season in 1968 with the world champion Tigers, finishing second in the AL with 36 homers, a .543 slugging average and 278 total bases.  In the later years of his career, he was twice named the AL's top designated hitter.

1972 Major League Baseball season: The 1972 Major League Baseball season was the first to have games cancelled by a player strike.  It was also the last season in which American League pitchers would hit for themselves on a regular basis; the designated hitter rule would go into effect the following season.

1975 Caribbean Series: The XVIII edition of the Caribbean Series ("Serie del Caribe") was played in 1975 .  It was held from February 1 through February 6 with the champions teams from the Dominican Republic, Águilas Cibaeñas; Mexico, Naranjeros de Hermosillo; Puerto Rico, Vaqueros de Bayamón and Venezuela, Tigres de Aragua.  The format consisted of 12 games, each team facing the other teams twice, and was played at Hiram Bithorn Stadium in San Juan, Puerto Rico.  For the first time in Series history, the designated hitter was adopted following the implementation of this rule by the American League during the 1973 MLB season.

Al Clark (umpire): Alan Marshall Clark (born January 9, 1948) is a former professional baseball umpire who worked in the American League from 1976 to 1999, and throughout both Major Leagues in 2000 and 2001, wearing uniform number 24 when the American League adopted them for its umpires in 1980, then retained the number when the NL and AL staffs were merged in 2000.  Clark umpired 3,392 major league games in his 26-year career.  He umpired in two World Series (1983 and 1989), two All-Star Games (1984 and 1995), five American League Championship Series (1979, 1982, 1987, 1992 and 1999), and three American League Division Series (1981, 1996 and 2000).  He was the home plate umpire in Nolan Ryan's 300th career win on July 31, 1990.

Defensive substitution: A defensive substitution in the game of baseball occurs when a currently non-playing player is placed into the field in place of another player, typically due either to injury or the appearance of a pinch hitter.  In the American League, a pinch hitter is usually substituted for the position player in whose place he batted (although another common substitution is pinch-hitting a utility infielder for a second baseman and subsequently switching him for the shortstop in the field while moving the shortstop over to the now-vacant second base position).  In the National League, which does not use the designated hitter rule, pinch hitters sometimes bat for pitchers. However, another common pitcher-substitution strategy in the NL is the double switch, in which a pitching change is coupled with a pinch-hitter who is also defensively substituted for a second player.

Larry Gowell: The Yankees called up Gowell from their minor league organization in 1972 to play as a September call-up.  Gowell made his major league debut on September 21 against the Milwaukee Brewers.  The game was held at County Stadium, with 4,185 people attending the game.  Gowell was called to replace Rusty Torres pitching and batting ninth in the bottom of the sixth inning.  He pitched two innings with one strikeout.  Felipe Alou was then called to pinch hit for Gowell in the top of the eighth inning.  The Yankees lost the game 6-4.  On October 4, as a starting pitcher (again facing Milwaukee) Gowell hit a double on a 3–2 count, hitting a fastball by pitcher Jim Lonborg for his first and only Major League hit and the last hit by a pitcher in a regular season American League game before the start of the designated hitter rule.  The baseball that Gowell hit now resides in the National Baseball Hall of Fame and Museum, in Cooperstown, New York.  Although Gowell allowed only one run during that game, the Yankees lost 1–0.  It was Gowell's only MLB decision.

Edgar Martínez Award: The Edgar Martínez Outstanding Designated Hitter Award, commonly referred to as the Edgar Martínez Award and originally known as the Outstanding Designated Hitter Award, has been presented annually to the most outstanding designated hitter (DH) in the American League (AL) in Major League Baseball (MLB) since 1973.  The award is voted on by club beat reporters, broadcasters and AL public relations departments.  All players with a minimum of 100 at bats at DH are eligible.  It was given annually by members of the Associated Press who are beat writers, broadcasters, and public relations directors.  The Associated Press discontinued the award in 2000, but it was picked up by the Baseball Writers' Association of America, which has administered it since.

Supporting paragraphs: History of the American League Designated hitter
Answer: Major League Baseball