Middlesex is a borough in northwestern Middlesex County near the borders of Somerset and Union counties. It lies between Dunellen, Piscataway, South Plainfield, Bound Brook, and Green Brook, giving it close ties to several regional business and transportation corridors. Route 28 passes through the borough, while nearby Route 22, Interstate 287, and NJ Transit service in neighboring Dunellen provide wider access. Middlesex contains established residential neighborhoods, schools, parks, small shopping areas, professional offices, and industrial properties. Boundaries formed by local waterways and older road patterns contribute to the borough's irregular shape. The community developed from rural settlements into a suburban municipality with growth tied to nearby railroads, highways, and employment centers. Middlesex Borough is separate from Middlesex County as a whole, a distinction that remains important in local identity. Its central location and mixed residential-industrial landscape connect the Raritan Valley with the more densely developed communities to the east.