| | | Clay County | IA | 19041 | | Spencer, IA 43980 | Spencer-Spirit Lake, IA 517 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=ClayCounty+IA |
| | | Clayton County | IA | 19043 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=ClaytonCounty+IA |
| | | Clinton County | IA | 19045 | | Clinton, IA 17540 | Davenport-Moline, IA-IL 209 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=ClintonCounty+IA |
| | | Crawford County | IA | 19047 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=CrawfordCounty+IA |
| | | Dallas County | IA | 19049 | | Des Moines-West Des
Moines, IA 19780 | Des Moines-West Des
Moines-Ames, IA 218 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=DallasCounty+IA |
| | | Davis County | IA | 19051 | | | | | nonmetro county (rural) | farm-dependent | https://maps.google.com/?q=DavisCounty+IA |
| | | Decatur County | IA | 19053 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=DecaturCounty+IA |
| | | Delaware County | IA | 19055 | | | | | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=DelawareCounty+IA |
| | | Des Moines County | IA | 19057 | | Burlington, IA-IL 15460 | Burlington-Fort Madison,
IA-IL 161 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=DesMoinesCounty+IA |
| | | Dickinson County | IA | 19059 | | Spirit Lake, IA 44020 | Spencer-Spirit Lake, IA 517 | Central | nonmetro county (rural) | recreation | https://maps.google.com/?q=DickinsonCounty+IA |
