| | | Clay County | IN | 18021 | | Terre Haute, IN 45460 | | Outlying | metro county (urban) | manufacturing-dependent | https://maps.google.com/?q=ClayCounty+IN |
| | | Clinton County | IN | 18023 | | Frankfort, IN 23140 | Lafayette-West
Lafayette-Frankfort, IN 320 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=ClintonCounty+IN |
| | | Crawford County | IN | 18025 | | | | | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=CrawfordCounty+IN |
| | | Daviess County | IN | 18027 | | Washington, IN 47780 | | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=DaviessCounty+IN |
| | | Dearborn County | IN | 18029 | | Cincinnati, OH-KY-IN 17140 | Cincinnati-Wilmington,
OH-KY-IN 178 | Outlying | metro county (urban) | recreation | https://maps.google.com/?q=DearbornCounty+IN |
| | | Decatur County | IN | 18031 | | Greensburg, IN 24700 | Indianapolis-Carmel-Muncie,
IN 294 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=DecaturCounty+IN |
| | | DeKalb County | IN | 18033 | | Auburn, IN 12140 | Fort
Wayne-Huntington-Auburn,
IN 258 | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=DeKalbCounty+IN |
| | | Delaware County | IN | 18035 | | Muncie, IN 34620 | Indianapolis-Carmel-Muncie,
IN 294 | Central | metro county (urban) | federal/state
government-dependent | https://maps.google.com/?q=DelawareCounty+IN |
| | | Dubois County | IN | 18037 | | Jasper, IN 27540 | | Central | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=DuboisCounty+IN |
| | | Elkhart County | IN | 18039 | | Elkhart-Goshen, IN 21140 | South
Bend-Elkhart-Mishawaka,
IN-MI 515 | Central | metro county (urban) | manufacturing-dependent | https://maps.google.com/?q=ElkhartCounty+IN |
