The above maps are a set of Exxon Maps issued from 1973 to 1989 for the State of Pennsylvania. The above page shows 24 maps covering 17 years, dating some of these maps is confusing. The spreadsheet showing all of the map codes and various dates on the maps is
The reason I used Pennsylvania maps is that this is the state for which I have the most Exxon maps, this is not a complete list of PA Exxon Maps. As in most of my collecting, I try to concentrate on one state for each company to better understand the series.
The following clickable link will open a Check-List type Spreadsheet that will include Map Codes, Copyright Dates and other descriptive information for the above pictured map series.
EXXON-Pennsylvania-Spreadsheet