The National Civic Union (in Spanish Unión Cívica Nacional) was an Argentine political party formed in 1891 as the result of a split in the Civic Union, and dissolved in 1916. It was initially based largely on the personality of its leader, Bartolomé Mitre.
On April 13, 1890, supporters of the Civic Union of the Youth established the Civic Union in a ceremony at the Buenos Aires Frontón. Leandro N. Alem was elected president and leaders were drawn from all tendencies within the anti-government movement, including Francisco A. Barroetaveña, José Manuel Estrada, Pedro Goyena, Aristóbulo del Valle, Bernardo de Irigoyen, Juan B. Justo, Lisandro de la Torre, and influential ex-president and general Bartolomé Mitre.
The same year, supporters of the Civic Union, led by Leandro Alem and Bartolomé Mitre, instigated the Revolution of the Park, an armed uprising that ousted president Juárez Celman and replaced him with vice president Carlos Pellegrini.
The Civic Union established a presidential ticket with Bartolomé Mitre and Bernardo de Irigoyen. However, Julio Argentino Roca, undisputed leader of the pro-government National Autonomist Party, made a deal with Mitre to form a "national unity" ticket headed by Mitre. After learning of the arrangement on April 16, Leandro Alem opposed it emphatically, splitting the Civic Union and forcing Mitre to abandon his candidacy.