The original teams in the Northwestern League were the Peoria Reds, the Toledo Blue Stockings, the Fort Wayne Hoosiers, the Saginaw Greys, and teams from Bay City, Michigan; Grand Rapids, Michigan; Quincy, Illinois; and Springfield, Illinois. The Blue Stockings won the championship.
In 1884, teams from Evansville, Indiana; Milwaukee, Wisconsin; Minneapolis, Minnesota; Muskegon, Michigan; St. Paul, Minnesota; Stillwater, Minnesota; Terre Haute, Indiana; and Winona, Minnesota joined the league. The new teams included the original Minneapolis Millers. Springfield and Toledo had left the league after the 1883 season.
Bay City disbanded from the league on July 22, and started a chain reaction. Evansville left on July 30, and Grand Rapids and Muskegon followed suit on August 2. The season ended when the Millers disbanded on September 3. St. Paul and Milwaukee left for the Union Association on September 27.