Rio is a town in the suburbs of Patras and a former municipality in Achaea, West Greece, Greece. Since the 2011 local government reform it is part of the municipality Patras, of which it is a municipal unit. The municipal unit has an area of 98.983 km². The municipal unit had a population of 14,219 in 2021. The campus of the University of Patras and the Casino Rio i…Rio is a town in the suburbs of Patras and a former municipality in Achaea, West Greece, Greece. Since the 2011 local government reform it is part of the municipality Patras, of which it is a municipal unit. The municipal unit has an area of 98.983 km². The municipal unit had a population of 14,219 in 2021. The campus of the University of Patras and the Casino Rio is located in Rio.