Sayreville is a borough in Middlesex County, in the U.S. state of New Jersey, in the New York metropolitan area. Sayreville is within the heart of the Raritan Valley region, located on the south banks of the Raritan River, and also located on the Raritan Bay. As of the 2020 United States census, the borough's population was 45,345, an increase of 2,641 (+6.2%) from the 2010 census count of 42,704,…