Mamaroneck mə-MAR-ə-nek is a village in Westchester County, New York, United States. The population was 18,929 at the 2010 census. As of 2019 its population was an estimated 19,131. It is located partially within the town of Mamaroneck and partially within the town of Rye. The portion in Rye is unofficially called "Rye Neck". The Rye Neck Union Free School District contains the Rye Neck portion of Mamaroneck and part of the city of Rye.