East Newark is a borough in the western part of Hudson County, in the U.S. state of New Jersey. The borough, a suburb of Newark, which sits across the Passaic River, is the second-smallest municipality by total area in the state. The Borough of East Newark was established on July 2, 1895, from portions of Kearny lying between the Erie Railroad's Newark Branch right of way and Harrison, based on the results of a referendum held the previous day.