Union Square: Plan of the Union Square, 12th ward. Signed by W.W. Thayer, surveyor and regulator, 4th district. [ID: 12B-564; PWD ERV: 1075976; Drawing No.: 2205], 1891 February 2, Drawer: N10, Folder: 5.1. Philadelphia Water Department 12B - Drawings Donation, FP.2019.002. Fairmount Park Historic Resources Archive. https://pprarchives.libraryhost.com/repositories/2/archival_objects/4868 Accessed April 20, 2025.