Route 439 is a short state highway in the communities of Elizabeth, Union and Hillside in Union County, New Jersey. The highway is known as the Bayway, North Avenue and Elmora Avenue from the Goethals Bridge and Interstate 278 (I-278) and does a half-loop around Elizabeth, with the designation terminating at an intersection with Route 27 in Elizabeth. The highway originated as part of Route 28 south of the current intersection with Route 28 and Route S24 north of that intersection to Route 82. The current designation of Route 439 was assigned in the 1953 renumbering.

Elizabeth is a city in and the county seat of Union County, in the U.S. state of New Jersey. As of the 2020 United States census, the city retained its ranking as the state's fourth-most-populous city behind neighboring Newark, Jersey City, and Paterson, with a population of 137,298, an increase of 12,329 (+9.9%) from the 2010 census count of 124,969, which in turn reflected an increase of 4,401 (3.7%) from the 120,568 counted in the 2000 census.