By: Tara LaLonde
Base map layers are common reference geographic information portrayed in many print and digital mapping projects (e.g. elevation, transportation networks, political boundaries, populated places etc.). Patrons often come (in person and virtually) to the Donald W. Hamer Center for Maps and Geospatial Information looking for base map information for current and historical time-periods. Library staff now have a new resource for recommending good base map layers for the state over the past 200 years – the Pennsylvania historic base map layers table.
The PSU historic base map project was conceived as an effort to explore the library’s physical and electronic collections of geographic information. The project was inspired by the Pennsylvania Geospatial Coordinating Board’s effort to implement authoritative modern base map layers for Pennsylvania. The coordinating board identified specific “themes” for categorizing map layers, such as transportation and hydrography. Similar thematic divisions to categorize base maps in the Pennsylvania historic base map layers.
Thematic categories are:
- Geographic Names
- Municipal Boundaries
- Land Ownership
- Land Use & Land Cover
- Remote sensing
Maps included in the table were judged by staff to be the best available examples of their category for a 10-year period (for maps published between 1900 and the present) or for a 50-year period (for maps published between 1800 and 1899). The results of the project identify both existing library holdings of historic base map information as well as serving as a guide for future collection development of missing historic base map information for Pennsylvania.
For more information on the process of reviewing content for inclusion in this project, check out our project page.