Following the May Revolution of 1810, the Viceroy had been replaced by the Primera Junta. The provinces had been moving towards full independence but royalist forces from the Viceroyalty of Peru have had the upper hand in the Upper Peru and were threatening the revolution.
Site of the Congress of Tucumán. Restored in 1941, it was made a National Monument.
On April 15, 1815, a revolution ended the mandate of Carlos María de Alvear and called a General Congress. Delegate deputies, each representing 15,000 inhabitants, were sent from all the provinces to the sessions that started on March 24, 1816. Nevertheless, some territories that formerly belonged to the Viceroyalty of the River Plate did not take part in the Congress: the delegates from the Banda Oriental ('Eastern Bank', today Uruguay) and other Liga Federal provinces, faithful to the democratic federalist project of José Gervasio Artigas were rejected based on formalities; Paraguay had already proclaimed its independence from Spain and remained isolated from the United Provinces politics. Representatives from Upper Peru Provinces (current Bolivia) were, however, present.
The congress was inaugurated in the house of Francisca Bazán de Laguna, consisted of 33 deputies, and its presidency rotated on a monthly basis. Because the congress had freedom to select the agenda, there were endless discussions. On July 9, it declared the independence of the United Provinces of South America, a name that was intended to appeal and eventually incorporate other Spanish American independentist regions that were not represented at the Congress.
At that time, the President of the Congress was Francisco Narciso de Laprida, delegate from San Juan Province. Subsequent discussions centred on the form of government that the young state should have and were the Congress and the executive power should reside.
The congress continued its work in Buenos Aires since 1817 and issued a Constitution in 1819, but the Constitution was rejected and the Congress was dissolved in 1820 after the Federal League Provinces of Santa Fe and Entre Ríos defeated a diminished Directorship army at the Battle of Cepeda, that staged the Unitarian (v.g. Centralist) versus Federal conflict on the battlefield.
The house where the declaration was made was rebuilt and is now a museum and monument. It is known as the "House of Tucumán".