The St. Louis Cardinals 1984 season was the team's 103rd season in St. Louis, Missouri and the 93rd season in the National League. The Cardinals went 84-78 during the season and finished 3rd in the National League East, 12½ games behind their arch-rivals, the Chicago Cubs. It was also the final season of the Columbia blue road uniforms for the Cardinals.
The cardinals were once in the American League
The context does not clearly state that the Cardinals played in the american league, it is totally possible that they played in a league entirely separate from the MLB for a decade before joining the MLB and National League. Context does not rule out this possibility