The topic developed is the Municipal Systems of South American countries. It deals with the IGRs, the predominant tradition in local administrative systems, the type of local government according to the political power of the Mayor, territorial and demographic characteristics of the Municipalities, local electoral regimes, decentralization and recentralization processes, legal framework supporting local autonomy, and municipal fiscal competencies and resources. The general objective is to carry out a comparative analysis between municipal systems, in order to have general notions and tendencies of the South American municipal system, overcoming the explanatory dichotomy of federal and unitary countries. The paper concludes that in South American municipal systems there is a local autonomy limited by fiscal and political centralization; there are recentralizing tendencies; mayors are actors, with high political power, but face challenges due to clientelism, scarce resources and territorial fragmentation; intermunicipal cooperation and metropolitan areas vary according to the country.