The American League of Major League Baseball begins using the designated hitter.

The American League of Professional Baseball Clubs, known simply as the American League (AL), is the younger of two leagues constituting 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.

Major League Baseball (MLB) is a professional baseball league in North America composed of 30 teams, divided equally between the National League (NL) and the American League (AL), 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. 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 Midtown Manhattan.

The designated hitter (DH) is a baseball player who bats in place of another position player, most commonly the pitcher. Unlike other players in a team's lineup, they generally only play as an offensive player and usually do not play defense as a fielder or a pitcher during a game. Due to their specialized offensive-only role, the designated hitter is generally expected to produce above average offensive stats and production compared to other players who play defense.