Pennsylvania (PA) historic base map layers are a set of historic maps and geospatial datasets intended to collectively provide comprehensive thematic and temporal coverage of the state for the period between 1800 and the present day. They were assembled to serve as an easy reference for anyone interested in historic geospatial information for PA and as a guide for future collection development to acquire new information sources that fill existing thematic and temporal gaps in our map and geospatial data holdings.
Each historic base map layer was selected to be the best representative example of its theme within a specific time period – at 10-year intervals between 1900 and 2019, and at 50-year intervals between 1800 and 1899. Preference was given to materials that are held by PSU Libraries or that were accessible through online sources available to PA Libraries staff and patrons at the time this work was completed (Spring, 2018).
Historic base map layers are representative of one of nine thematic categories, which are based on categories identified by the PA Geospatial Coordinating Board for the Pennsylvania Base map project. These categories are:
- Geographic Names
- Municipal Boundaries
- Land Ownership
- Land Use & Land Cover
- Remote Sensing
Historic base map layers come from many different sources and are at a variety of scales. When possible, all base map layers provide complete coverage of Pennsylvania. Most are a single map, while some layers are a group or collection of maps that collectively provide complete coverage (for example, a set of county maps that cover the entire state.)
Individual layers were selected by a process where potentially appropriate materials were identified within the library catalog through examination of all map/GIS items within specific LOC number ranges, augmented by material identified through manual keyword searches and searching online sources.
The result of this project was a table of historic base map layers providing coverage of the state for most time periods within the study. A few categories are not well-represented; for example, there are no comprehensive sources of land ownership data in Pennsylvania except in the very earliest periods within the study. A few categories are not well-represented; for example, there are no comprehensive sources of land ownership data in Pennsylvania except in the very earliest periods.
Using this table
The table is divided into three sections: “Historic Base map Layers”, “Additional Layers”, and “About”.
The “Historic Base map Layers” section contains the best representative base map layer for each time period. Time periods are ordered in rows and map themes are ordered in columns. A map title, library call number, scale (if known), year and coverage are supplied for each map layer.
Identifying the appropriate map layers
Geographic Names includes maps that are useful for determining placenames.
Landmarks primarily includes maps that show parks and recreational areas.
Transportation includes maps that show roads. Depending on the map’s age, they may also show railroads and canals, and/or distinguish roads by their type.
Hydrography includes features like rivers, streams, lakes and canals. Some maps include watershed boundaries.
Municipal Boundaries include the lines separating counties, municipalities, cities and boroughs.
Land Ownership maps shows the boundaries of lands ownership, such as parcels and tracts.
Elevation or topographic maps show the height of land above sea level, typically through the use of contour lines.
Land Use & Land Cover includes maps that show how land is used by humans and maps that are focused on vegetation or man-made constructions like buildings.
Remote Sensing resources included within this set are collections of aerial images, typically produced by a federal imaging project like NAIP or NAPP.
Ben Carlsen, Tara Lalonde, Heather Ross, Nathan Piekielek
This project was supported by the Penn State University Libraries.