United States Post Office 37 Winwood Plz, Bakerstown, PA15007 The United States Post Office located in Winwood Plaza is a location for shipping and mail drop-off only. There are no…More mail carriers at this location. This post office offers online post office boxes. The location has flexible hours, and is open on Saturday mornings. The United States Post Office is known for its shipping service with flat-rate boxes. Its shipping prices are reduced at busy times of the year for mail carrying, including the holiday season.