US Post Office is located at 15 Main St, Gilsum, NH. This business specializes in Post Offices. US Post Office is open Mon, 8:05am-4pm; Tue, 8:05am-4pm; Wed, 8:05am-4pm; Thu, 8:05am-4pm; Fri, 8:05am-4pm; Sat, 9am-11am; Sun, Closed and accepts American Express, Discover, Mastercard and Visa.