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 derives from the French name La Grande Île, as Grand Island is the largest island in the Niagara River and third largest in New York state. The phrase La Grande Île appears on the town seal.