On May 28, 1968 — American League owners agree to divide the circuit into two divisions and reduce its schedule to 156 games. The following divisional alignment is set for the 1969 season: Eastern Division: Baltimore Orioles, Boston Red Sox, Cleveland Indians, Detroit Tigers, New York Yankees, Washington Senators. Western Division: California Angels, Chicago White Sox, Kansas City Royals, Minnesota Twins, Oakland Athletics, Seattle Pilots.
Source:
Baseball Reference May 28