| | Jersey County | IL | 17083 | | St. Louis, MO-IL 41180 | St. Louis-St.
Charles-Farmington, MO-IL 476 | Outlying | metro county (urban) | nonspecialized | https://maps.google.com/?q=JerseyCounty+IL |
| | Kane County | IL | 17089 | Elgin, IL 20994 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=KaneCounty+IL |
| | Kankakee County | IL | 17091 | | Kankakee, IL 28100 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=KankakeeCounty+IL |
| | Kendall County | IL | 17093 | Elgin, IL 20994 | Chicago-Naperville-Elgin,
IL-IN 16980 | Chicago-Naperville,
IL-IN-WI 176 | Central | metro county (urban) | nonspecialized | https://maps.google.com/?q=KendallCounty+IL |
| | Knox County | IL | 17095 | | Galesburg, IL 23660 | | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=KnoxCounty+IL |
| | 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 |
| | 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 |
| | Lee County | IL | 17103 | | Dixon, IL 19940 | Dixon-Sterling, IL 221 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=LeeCounty+IL |
| | Livingston County | IL | 17105 | | Pontiac, IL 38700 | Bloomington-Pontiac, IL 145 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=LivingstonCounty+IL |
| | Logan County | IL | 17107 | | Lincoln, IL 30660 | Springfield-Jacksonville-Lincoln,
IL 522 | Central | nonmetro county (rural) | nonspecialized | https://maps.google.com/?q=LoganCounty+IL |