US Post Office is located at 1248 5Th St, Santa Monica, CA. This location is in the Downtown Santa Monica neighborhood. This business specializes in Post Offices. US Post Office is open Mon, 9am-6pm; Tue, 9am-6pm; Wed, 9am-6pm; Thu, 9am-6pm; Fri, 9am-6pm; Sat, 9am-3pm; Sun, Closed and accepts American Express, Discover, Mastercard and Visa.