County Thematic Maps (pre-2000) - Notes

The County Thematic Map Section continues our visualization of statistical information for the nine counties in the Map Center’s Region. Using joined databases from several sources we map common themes such as Housing, Education and Income for each county to the Census Tract Level.

Census Tracts are defined by the Census Bureau as "statistical subdivisions of selected counties which are established by a local committee of data users". They are based on several factors such as a threshold population count and established political boundaries within a county. Census Tracts provide a relatively stable basis for tabulating the decennial census data both historically and in an estimating or projecting context. Census Tracts also provide the framework for Census Blocks, the smallest of the Census subdivisions.

On the twelve thematic maps for each county, the county seat and boundaries for Minor Civil Divisions (MCDs): townships, boroughs, towns, cities are included for reference. A link to each county's MCD reference map is provided in the Selector window and at the bottom of each display page. With the exception of the Wyoming and Lackawanna Valleys, Northeastern Pennsylvania is largely rural which means that one Census Tract includes several MCDs. Within the urbanized areas the opposite is true - there are several to many tracts within one MCD.

The source for the Census data is GeoLytics' CensusCD Versions 1 and 3. Version 1 provided 1997 estimated data and Version 3 provided 1999 estimated data to Tract level. For some categories only 1990 Census data is available. 2000 Census data was used for population density. As the Census Bureau releases more data to tract level we will use it to replace the estimates and 1990 Census values.

The maps were generated in ArcGis, one of ESRI’s GIS software packages. The geographic line work is from the TIGER 2000 data set, which was acquired from ESRI's Geography Network. This version "smooths" the polygons where previous versions left "holes" for water bodies. NOTE: There was a change in the Carbon-Monroe county line from 1990 to 2000. The "notch" that was in the NE-SW boundary line was removed by transferring a piece of Carbon County (Penn Forest Twp) to Monroe County (Polk Twp). The result is an "extra" polygon in maps with pre-2000 data.

The maps employ the choropleth* technique. The data is broken into four ranges using "natural breaks" as a classification scheme. The range values for a particular theme varies among counties. However, graphic and substantive consistency across counties is given highest priority for the Project.

*"Choropleth" is derived from the Greek words CHOROS (place) and PLETH (value). It refers to statistical maps that match distinctive color or shading, representing data, to an enumeration unit which is usually a statistical or administrative area (Census Tracts in this case). See the regional business map page for another example and further information on this technique.