| | Lake County | IL | 17097 | Lake County, IL 29404 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=LakeCounty+IL |
| | Lake County | IN | 18089 | Lake County-Porter
County-Jasper County, IN 29414 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=LakeCounty+Indiana |
| | LaPorte County | IN | 18091 | | Michigan City-La Porte,
IN 33140 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=LaPorteCounty+IN |
| | LaSalle County | IL | 17099 | | Ottawa, IL 36837 | Chicago-Naperville,
IL-IN-WI 176 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=LaSalleCounty+Illinois |
| | McHenry County | IL | 17111 | Chicago-Naperville-Schaumburg,
IL 16984 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=McHenryCounty+IL |
| | Newton County | IN | 18111 | Lake County-Porter
County-Jasper County, IN 29414 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=NewtonCounty+Indiana |
| | Porter County | IN | 18127 | Lake County-Porter
County-Jasper County, IN 29414 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | manufacturing-dependent | https://maps.google.com/?q=PorterCounty+Indiana |
| | Putnam County | IL | 17155 | | Ottawa, IL 36837 | Chicago-Naperville,
IL-IN-WI 176 | Outlying | nonmetro county (rural) | manufacturing-dependent | https://maps.google.com/?q=PutnamCounty+Illinois |
| | Will County | IL | 17197 | Chicago-Naperville-Schaumburg,
IL 16984 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=WillCounty+IL |