Windsor, also known as New Windsor, is a village in Rivoli Township, Mercer County, Illinois, United States. The population was 748 at the 2010 census, up from 720 in 2000. The official name is the Village of Windsor, but New Windsor is also used by the village such as the New Windsor Fire Department. The US Postal service shows New Windsor, Illinois as 61465 but the US Census Bureau calls it Windsor Village to differentiate it with the city of Windsor and Windsor Township, both in Shelby County.