Where county lines corresponded with linear features in other coverages, those arcs were used. To fill in gaps, boundaries were digitized from USGS 100,000-scale quadrangle maps. 1990 was the approximate date the coverage was compiled. The county lines have been in place for several decades. Polygon and chain-node topology present.
Every polygon has a label and all polygons are closed.
All counties are in the dataset. Checked linework against 100K quad map acetates. Placement errors for arcs were found in the 1st edition of the PLSS coverage on which county boundaries are partially based. Not all of the errors have been identified or corrected in the counties coverage as of this writing. The coverages listed below in the Process Step contributed linework.