Southeastern Pennsylvania Processing & Distribution Center - Credit: Wikimedia Commons
Southeastern was a United States Postal Service regional Processing and Distribution Center (P&DC) in Tredyffrin Township, Chester County, Pennsylvania, United States, near Devon. It was primarily known for its post mark on mail originating in many ZIP codes in the region. The retail post office remains open at the location of the former P&DC. Read more on Wikipedia
Source: en.wikipedia.org