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

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. <SEP>  The rule allows teams to have one player, known as the designated hitter (abbreviated DH), to bat in place of the pitcher. In baseball, the designated hitter rule is the common name for Major League Baseball Rule 5.11, adopted by the American League in 1973.  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. <SEP> 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. <SEP> 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.