The first assent was in march 25 of 1621, The jesuit priest San Roque González de Santa Cruz, founded in this place, the jesuitic reduction “ Nuestra Señora de la Anunciación de Itapua” but it not prospered, and has moved to the other shore of the Parana where 6 years after was founded the Encarnación city. After of 2 centuries of this foundation, is created a new assent, that in several oportunities, changes your name, like Rinconada, Garganta, Tranquera de San José, Trinchera de itapua, Trinchera de los Paraguayos, and untill that finally was designed with the name of Trinchera de San José. By that time, this was inside of the called national territory and is part of Corrientes, in november 8 of 1870, the executive and the legislature of corrientes dictate a law of creation of the Candelaria departament and it designated to Trincheras de San José as departamental capital, of that way started your official existence. In setember 7 of 1879, the legislature of corrientes, that has joined to Misiones (with the name of Candelaria)decide give the name of Posadas, to the town of Trincheras de San José and this law was promulgated in setember 22 of 1879, the name responds at the first suprem director of the river plate, Gervasio Posadas, that where put the limits of provinces annexed the towns of Misiones to Corrientes. The fundation of Posadas city, was officially considerated in noviember 8 of 1870. - The land surveyor Francisco Lezcano to trace the demarcation of Trinchera de San José, according the instructions recived of Corrientes in 1871, established blocks of 100 yard ( 86,60 mts.) and a urban centric plant between four avenues, today called Roque Perez at North, Roque Sáenz Peña at East, Mitre at South, and Corrientes at west.