US Post Office is located at 103 W Main St, Westfield, PA. This business specializes in Post Offices. US Post Office is open Mon, 8am-3:59pm ; Tue, 8am-3:59pm ; Wed, 8am-3:59pm ; Thu, 8am-3:59pm ; Fri, 8am-3:59pm ; Sat, 8:05am-10:05am ; Sun, Closed. and accepts American Express, Discover and Visa.