The Union Association became a third Major League in 1884, but the league was hardly on the same level as the National League of the American Association. Henry Lucas was the force behind the new league which was created in part to challenge the reserve clause which tied players to one team.

Lucas however, seemed to have ulterior motives hoping to force his way into the National League. The Union League may have had top level talent but hardly looked like a Major League as teams drifted in and out throughout the season leading many to deride the UA as the "Onion League".

The St. Louis Maroons were the only team capable of competing in a high level as they won their first 20 games and went on to walk away with the pennant with a record of 94-19.