US Post Office is located at 1965 Morris Ave # A, Union, NJ. This business specializes in Post Offices. US Post Office is open Mon, 9am-4:05pm; Tue, 9am-4:05pm; Wed, 9am-4:05pm; Thu, 9am-4:05pm; Fri, 9am-4:05pm; Sat, Closed; Sun, Closed and accepts American Express, Discover, Mastercard and Visa.