Thanks to Cathy from the Ericson Library in Boone for her help.
The base map is a copy (19 Oct 2000) of one found at the
Ericson Library in Boone, Boone County, Iowa.
The colored borders of the townships, cities and county were added to a
scanned copy of the base map.  Please see the lower right corner of the image for
full source information of the original map.