

In 1905, the Lincoln section of Middlesex organized a volunteer fire company and that set the organization of four other fire companies in the borough. Virgin School was the first parochial school built in 1954. As the Borough grew new schools were constructed to accommodate many more students. The original Pierce School was known as the East Bound Brook School House and The Parker House was also used for education until it was converted into a two-family house. The Harris Lane School was a one-room schoolhouse that was the oldest school in Middlesex County, dating back to its construction in the 1790s. The borough was named after Middlesex, England. Middlesex was incorporated as a borough by an act of the New Jersey Legislature on April 9, 1913, from portions of Piscataway, based on the results of a referendum held on May 6, 1913. As of the 2020 United States census, the borough's population was 14,636, its highest decennial count and an increase of 1,001 (+7.3%) from the 2010 census count of 13,635, which in turn reflected a decline of 82 (−0.6%) from the 13,717 counted in the 2000 census.

It is located within the Raritan Valley region. Middlesex is a borough in Middlesex County, in the U.S.
