EarthWorks Geospatial Catalog

Public Land Survey System (PLSS) Boundaries: Illinois, 2003

This data set contains Illinois Public Land Survey System (PLSS) boundaries and designations in line and polygon feature classes. THESE DATA HAVE POSITIONAL INACCURACY OF UP TO 600 FEET IN SOME AREAS OF THE STATE. THEY ARE NOT TO BE USED AT SCALES GREATER THAN 1:62,500. THE DATA ARE NOT APPROPRIATE AS A GEODETIC, LEGAL OR ENGINEERING BASE. The polygon attribute data include meridian, township, range, section and county number (FIPS) designations. The line attributes indicate line type, including the state line, county lines, township and range lines, section lines, Indian treaty boundaries, base lines, principal meridians, and boundaries between areas mapped from different principal meridians. The nominal scale is 1:62,500. As of 2003, the data are typically distributed in geographic coordinates (longitude and latitude), decimal degrees, and the North American Datum (NAD) of 1983, and this is the default spatial reference of the ArcSDE feature dataset in which the data are stored. The data were originally developed, however, in a custom Lambert Conformal Conic projection and were distributed in that coordinate system for several years. The data were digitized in the late 1960s, early 1970s, and in 1984-85 from 7.5- and 15-minute USGS topographic quadrangles. Errors in the location of a given feature are dependent on the accuracy of the original maps and on the accuracy of digitizing. Estimates are that features have an average locational error of approximately plus/minus 100 feet. Some areas of the state have a locational error of approximately 600 feet. In areas of French colonization land grants, where PLSS sections were not actually surveyed, sections and section lines have been added (estimated). A graphic overview of the township and range system in Illinois is included in the file c451.pdf
Illinois Geospatial Data Clearinghouse
Illinois, United States
Boundaries, Planning cadastre, and Public land survey system
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