The National League of Professional Base Ball Clubs formed on February 2, 1876 with eight charter teams located in Boston, Chicago, Cincinnati, Hartford, Louisville, New York, Philadelphia, and St. Louis. After playing the 1876 season in Hartford, Connecticut, the Hartford Dark Blues played the 1877 season in Brooklyn as the Brooklyn Hartfords before disbanding at the end of the season.

The National League’s formation meant the end of the old National Association, which lasted only five seasons. The remaining clubs in the NA shut down or reverted to amateur or minor league status.