Grand Island is an island town in Erie County, New York, United States. As of the 2020 census, the town's population was 21,389 representing an increase of 5.00% from the 2010 census figure. The town's name is derived from the French name La Grande Île; Grand Island is the largest island in the Niagara River and the third largest in New York state. The phrase La Grande Île appears on the town seal.