United Provinces of the Río de la Plata replaces Viceroyalty of the Río de la Plata
The United Provinces of the Río de la Plata (Spanish: Provincias Unidas del Río de la Plata), earlier known as the United Provinces of South America (Spanish: Provincias Unidas de Sudamérica), was a name adopted in 1816 by the Congress of Tucumán for the region of South America that declared independence in 1816, with the Sovereign Congress taking place in 1813, during the Argentine War of Independence (1810–1818) that began with the May Revolution in 1810. It originally comprised rebellious territories of the former Spanish Viceroyalty of the Río de la Plata dependencies and had Buenos Aires as its capital. 
The name "Provincias del Río de la Plata" (formally adopted during the Cortes of Cádiz to designate the Viceroyalty of the Río de la Plata) alludes to the Junta Provisional Gubernativa de las Provincias del Río de la Plata  or Primera Junta. It is best known in Argentinean literature as Provincias Unidas del Río de la Plata ("United Provinces of the River Plate" i.e. river of silver), this being the most common name (since 1811) in use for the country until the enactment of the 1826 Constitution. The Argentine National Anthem refers to the state as "the United Provinces of the South". The Constitution of Argentina recognises Provincias Unidas del Río de la Plata as one of the official names of the country, referred to as "Argentine Nation" (Nación Argentina) in modern legislation.Government
The change from the Viceroyalty into the United Provinces was not merely a change of governors, but a revolutionary process that would replace the Spanish monarchy with an independent republic. 
The main influences in this were the Enlightenment in Spain, promoting new ideas, and the Peninsular War that left Spain without a legitimate king after the Abdications of Bayonne. The concept of separation of powers gradually became a tool to prevent despotism.: 12 The new political situation generated great political conflict between the cities for two reasons. First, the vacatio regis of Ferdinand VII and the French King of Spain, Joseph Bonaparte, there was no clear view about who was the king. Some people thought that it passed to other offices of the Spanish monarchy, while others held the notion of the retroversion of the sovereignty to the people: sovereignty returned to the people, who had now the right to self-governance temporally. : 14 But, in 1810 under the establishment of the new doctrine of popular sovereignty throughout the Spanish empire, the Spanish government summoned all the nations of America and Spain, to establish Spanish courts for the whole empire, but on the contrary, the patriots, under the same right of popular sovereignty, thought that any nation, both in Spain and America, had the right to self-government and to establish their own country.
succeeds supersedes substitutes takes over fills in for