Bill Board type sign.
Photos 1 & 2 are magnifications of Photo 4 to provide additional detail of the Mail Pouch sign. Photo 3 is a different photo taken by the same photographer on the same day.
The GPS coordinates are approximate as is the location of Photo 5 (Google Earth street view). W. Carson St. has undergone significant changes over the years and it is difficult to determine exactly where the Mail Pouch sign was located. Glen Manor Ave. no longer exists. The location for the coordinates is in the Esplen Section of Pittsburgh.