Iguazu Falls, Iguassu Falls, are waterfalls of the Iguazu River located on the border of the Brazilian State of Paraná and the Argentine Province of Misiones. The falls divide the river into the upper and lower Iguazu. The Iguazu River originates near the city of Curitiba. It flows through Brazil for most of its course. Below its confluence with the San Antonio River, the Iguazu River forms the boundary between Brazil and Argentina.