Twin Rivers is a census-designated place and unincorporated area located within East Windsor Township, in Mercer County, New Jersey. As of the United States 2000 Census, the CDP population was 7,422. Twin Rivers was the first Planned Unit Development in New Jersey. Twin Rivers apartments for rent comparison page shows most up to date rent information on Twin Rivers apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.