The Federal Party was founded on 1 October 1899 by Luis Muñoz Rivera and other former members of the Autonomist Party during US military rule of the island following the Spanish–American War. The Federal Party supported greater self-rule for the island. The party was regarding as having among its members the former Spanish colonial elite consisting of large sugar plantation owners and hacendados who had enslaved the Black residents of the Island.
In February 1904, the party was reconstituted as the Union of Puerto Rico, or Union Party.
- Ileana M. Rodriguez-Silva. Silencing Race: Disentangling Blackness, Colonialism, and National Identities in Puerto Rico. New York: Palgrave Macmillan. 2012. p. 178.
- Bolivar Pagan. Historia de los Partidos Políticos Puertorriqueños (1898–1956). San Juan, Puerto Rico: Litografía Real Hermanos, Inc. 1959. Tomo I. p. 15.