Lawrenceville is a census-designated place and unincorporated area located within Lawrence Township in Mercer County, New Jersey. As of the 2010 United States Census, the CDP population was 3,887. Lawrenceville is located roughly halfway between Princeton and Trenton. Lawrenceville is also known as the "village of Lawrenceville." Its core is the Main Street Historic District, which was listed in the New Jersey and National Registers of Historic Places in 1972, one of the first registered historic districts in New Jersey .