1998. Illinois State Geological Survey. This polygon data layer represents the boundary for Illinois in 1998. The dataset was originally published by the Illinois State Geological Survey ...
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2003. Illinois State Geological Survey. This line data layer represents county boundaries for Illinois in 2003. The dataset was originally published by the Illinois State Geological Surve... Illinois State Geological Survey.
1996. Illinois State Geological Survey. This line data layer represents generalized railroads for Illinois in 1996. The dataset was originally created by the Illinois State Geological Sur...
1996. Illinois State Geological Survey. This line data layer represents interstates and toll roads for Illinois in 1996. The dataset was originally created by the Illinois State Geologica...