Lawrenceville is a census-designated place and unincorporated area located within Lawrence Township in Mercer County, New Jersey. As of the United States 2000 Census, the CDP population was 4,081. Lawrenceville is located roughly halfway between Princeton and Trenton. Lawrenceville apartments for rent comparison page shows most up to date rent information on Lawrenceville apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.