US Post Office is located at 1000 Progress Dr, Liberty, MO. This business specializes in Post Offices. US Post Office is open Mon, 8am-5pm; Tue, 8am-5pm; Wed, 8am-5pm; Thu, 8am-5pm; Fri, 8am-5pm; Sat, 9am-12am; Sun, Closed and accepts American Express, Discover, Mastercard and Visa.