Groenlo is a city in the municipality of Oost Gelre, situated in the eastern part of the Netherlands, on the German border, within a region in the province of Gelderland called the Achterhoek. Groenlo was a municipality until 1 January 2005, when it merged with Lichtenvoorde. Until 19 May 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.