Groenlo is a city in the municipality of Oost Gelre, situated in the eastern part of the Netherlands on the German border, a region in the province of Gelderland called the Achterhoek (literally:back corner). Groenlo was a municipality until January 1, 2005, when it merged with Lichtenvoorde. Until May 19, 2006 Groenlo was the official name of Oost Gelre. As of 1 January 2006 Groenlo, including its hamlet Zwolle, counted a population of 10.067. Groenlo is known locally and historically as Grolle, Groll or Grol.