The National Labor Union attempted to join all labor unions into one large umbrella union. It was initially successful in lobbying Congress to establish the eight hour work day; but this success soon backfired when employers cut wages. The NLU took the position that it could only advance its agenda through political reform. This was unsatisfactory to many workers who wanted immediate work reform, not slow government reform. Workers left the NLU en masse, most of whom joined the Knights of Labor described below.
The Knights of Labor, originally organized by Uriah S. Stevens, was initially successful. The Knights organization ultimately failed due to lack of organization and disagreement within its ranks. Strikes and walkouts began happening spontaneously without any previous organization, and most such strikes ultimately failed. The final blow to the Knights came during the Haymarket Affair when several people were killed. One of those arrested was an anarchist who had a Knights of Labor card. The Knights thus were labeled as anarchists, a taint from which they could not recover. Members left in droves, many of whom joined the International Workmen of the World. The organization finally closed its doors in 1949, although it had been ineffective for many years previously.
The American Federation of Labor, organized by Samuel L. Gompers, was most successful because he attempted to work for immediate goals and reform, rather than long term political goals. He supposedly once said that he wanted "bread and butter in the here and now," not "pie in the sky in the sweet bye and bye." Immediate goals made the AFL attractive and ultimately successful.