Hightstown is a borough in Mercer County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 5,494, reflecting an increase of 278 (+5.3%) from the 5,216 counted in the 2000 Census, which had in turn increased by 90 (+1.8%) from the 5,126 counted in the 1990 Census. Hightstown was incorporated as a borough by an act of the New Jersey Legislature on March 5, 1853, within portions of East Windsor Township. The borough became fully independent c. 1894.