Middlesex County is a county in New Jersey, United States, about 30 miles southwest of New York City along the lower Raritan River. It had a population of 863,162 at the 2020 census, an estimated 883,335 by 2025, and covers 322.87 square miles (836.2 km2) centred near 40\u00b024\u2032N 74\u00b022\u2032W.<\/p>\n
New Brunswick is the county seat, home to Rutgers University’s main campus; its postal code is 08901. The county holds 3 cities, 10 townships and 12 boroughs — 25 municipalities in all, since every acre of New Jersey belongs to one — and it runs on Eastern Time. Its FIPS code is 34023.<\/p>\n
All 25 municipalities are incorporated; New Jersey has no unincorporated county territory, so “Township” and “Borough” below are legal municipal types, not subdivisions of a larger town. New Brunswick and Perth Amboy are cities; South Amboy is also a city despite its small size.<\/p>\n
| Place<\/th>\n | Type<\/th>\n | Pop.<\/th>\n | ZIP<\/th>\n<\/tr>\n<\/thead>\n |
|---|---|---|---|
| Carteret<\/td>\n | Borough<\/td>\n | 25,326<\/td>\n | 07008<\/td>\n<\/tr>\n |
| Cranbury<\/td>\n | Township<\/td>\n | 3,842<\/td>\n | 08512<\/td>\n<\/tr>\n |
| Dunellen<\/td>\n | Borough<\/td>\n | 7,637<\/td>\n | 08812<\/td>\n<\/tr>\n |
| East Brunswick<\/td>\n | Township<\/td>\n | 49,715<\/td>\n | 08816<\/td>\n<\/tr>\n |
| Edison<\/td>\n | Township<\/td>\n | 107,588<\/td>\n | multiple — see note<\/td>\n<\/tr>\n |
| Helmetta<\/td>\n | Borough<\/td>\n | 2,455<\/td>\n | 08828<\/td>\n<\/tr>\n |
| Highland Park<\/td>\n | Borough<\/td>\n | 15,072<\/td>\n | 08904<\/td>\n<\/tr>\n |
| Jamesburg<\/td>\n | Borough<\/td>\n | 5,783<\/td>\n | 08831<\/td>\n<\/tr>\n |
| Metuchen<\/td>\n | Borough<\/td>\n | 15,049<\/td>\n | 08840<\/td>\n<\/tr>\n |
| Middlesex<\/td>\n | Borough<\/td>\n | 14,636<\/td>\n | 08846<\/td>\n<\/tr>\n |
| Milltown<\/td>\n | Borough<\/td>\n | 7,037<\/td>\n | 08850<\/td>\n<\/tr>\n |
| Monroe Township<\/td>\n | Township<\/td>\n | 48,594<\/td>\n | 08831<\/td>\n<\/tr>\n |
| New Brunswick<\/td>\n | City · seat<\/td>\n | 55,266<\/td>\n | 08901<\/td>\n<\/tr>\n |
| North Brunswick<\/td>\n | Township<\/td>\n | 43,905<\/td>\n | 08902<\/td>\n<\/tr>\n |
| Old Bridge<\/td>\n | Township<\/td>\n | 66,876<\/td>\n | 08857<\/td>\n<\/tr>\n |
| Perth Amboy<\/td>\n | City<\/td>\n | 55,436<\/td>\n | 08861<\/td>\n<\/tr>\n |
| Piscataway<\/td>\n | Township<\/td>\n | 60,804<\/td>\n | 08854<\/td>\n<\/tr>\n |
| Plainsboro<\/td>\n | Township<\/td>\n | 24,084<\/td>\n | 08536<\/td>\n<\/tr>\n |
| Sayreville<\/td>\n | Borough<\/td>\n | 45,345<\/td>\n | 08872<\/td>\n<\/tr>\n |
| South Amboy<\/td>\n | City<\/td>\n | 9,411<\/td>\n | 08879<\/td>\n<\/tr>\n |
| South Brunswick<\/td>\n | Township<\/td>\n | 47,043<\/td>\n | multiple — see note<\/td>\n<\/tr>\n |
| South Plainfield<\/td>\n | Borough<\/td>\n | 24,338<\/td>\n | 07080<\/td>\n<\/tr>\n |
| South River<\/td>\n | Borough<\/td>\n | 16,118<\/td>\n | 08882<\/td>\n<\/tr>\n |
| Spotswood<\/td>\n | Borough<\/td>\n | 8,163<\/td>\n | 08884<\/td>\n<\/tr>\n |
| Woodbridge<\/td>\n | Township<\/td>\n | 103,639<\/td>\n | multiple — see note<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n Do not confuse the Borough of Middlesex, one of the county’s 25 municipalities and population 14,636, with Middlesex County itself. Two other Middlesex Counties exist in the United States, in Massachusetts and Connecticut, and neither shares any government with this one. Within the county, some townships contain well-known unincorporated sections that people search for by name even though they are not separate municipalities: Edison holds Clara Barton, Menlo Park Terrace and Stelton; Woodbridge Township holds Avenel, Colonia, Fords, Iselin, Keasbey, Port Reading and Sewaren, each with its own ZIP code and identity despite falling under one municipal government.<\/p>\n ZIP Codes<\/h2>\nEvery ZIP above serves an active post office; the county has no hamlet without postal coverage, unlike more rural counties.<\/p>\n Geography<\/h2>\nMiddlesex County sits on the Inner Coastal Plain, mostly flat to gently rolling, with elevation from sea level to about 300 feet. The Raritan River bisects the county west to east, passing New Brunswick and Piscataway before widening into Raritan Bay between Perth Amboy and South Amboy. Land covers 309.22 square miles of the total; water, mostly the bay and the river itself, covers 13.65 square miles.<\/p>\n Union County borders it to the northeast, Somerset County to the northwest, Mercer County to the southwest, and Monmouth County to the south. Across Raritan Bay and the Arthur Kill to the northeast lies Staten Island, New York — a water boundary, not a land one.<\/p>\n Demographics<\/h2>\nThe county counted 863,162 residents at the 2020 census, the third-highest total of New Jersey’s 21 counties, and the Census Bureau estimated 883,335 by 2025. Edison (107,588) and Woodbridge Township (103,639) are the two largest communities, together holding roughly a quarter of the county’s population. Median household income is $93,418, somewhat below the statewide median of roughly $97,000. Population density is about 2,791 people per square mile, among the denser counties in the state.<\/p>\n Economy & Local Life<\/h2>\nMiddlesex County’s economy produced a gross domestic product of $59.0 billion in 2021, second-highest among New Jersey’s counties. Healthcare and pharmaceuticals anchor it: Robert Wood Johnson University Hospital and Rutgers Robert Wood Johnson Medical School sit in New Brunswick alongside Johnson & Johnson’s world headquarters, and Bristol-Myers Squibb maintains a major research campus in the county. Rutgers University’s main campus, spread across New Brunswick and Piscataway, enrolls more than 50,000 students and is the county’s largest single employer. Warehousing and distribution cluster along the New Jersey Turnpike corridor through Edison, Cranbury and South Brunswick, close to the Port of New York and New Jersey. The Middlesex County Fair runs each August at the county fairgrounds in East Brunswick, the area’s largest annual community event.<\/p>\n History<\/h2>\nNew Jersey organised Middlesex as one of its original four counties in 1683, alongside Bergen, Essex and Monmouth, and named it for Middlesex, England. Perth Amboy served as capital of the Province of East Jersey from 1686 until New Jersey’s two colonial provinces united in 1702, and it remained a co-capital afterward into the Revolutionary era. Rutgers University traces to 1766, when the colonial legislature chartered Queen’s College in New Brunswick as one of the nine colleges founded before American independence. British and Hessian forces occupied New Brunswick through the winter of 1776 into 1777 during George Washington’s retreat across New Jersey, and skirmishes along the Raritan continued through the war.<\/p>\n Getting There<\/h2>\nThe New Jersey Turnpike (Interstate 95) crosses the county with five exits, and the Garden State Parkway runs through with nine interchanges. Interstate 287 crosses the northern county through Piscataway and Edison, and US Route 1 runs the length of the county through New Brunswick and Edison as a major commercial corridor. Route 9, Route 18, Route 27 and Route 130 provide additional county-wide access.<\/p>\n
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