Red imported fire ants are native to the tropical areas of Central and South America, where they have an expansive geographical range that extends from southeastern Peru to central Argentina, and to the south of Brazil. In contrast to its geographical range in North America, its range in South America is significantly different. It has an extremely long north–south range, but a very narrow east–west distribution. The northernmost record of the red imported fire ant is Porto Velho in Brazil, and its southernmost record is Resistencia in Argentina; this is a distance of about . In comparison, the width of its narrow range is about , and this is most likely narrower into southern Argentina and Paraguay and into the northern areas of the Amazon River basin. Most known records of the red imported fire ant are around the Pantanal region of Brazil. However, the interior of this area has not been examined thoroughly, but it is certain that the species occurs in favourable locations around it. The Pantanal region is thought to be the original homeland of the red imported fire ant; hydrochore dispersal via floating ant rafts could easily account for the far south populations around the Paraguay and Guaporé Rivers. The western extent of its range is not known exactly, but its abundance there may be limited. It may be extensive in easternmost Bolivia, owing to the presence of the Pantanal region.