Source Information
Ancestry.com. Northern District, Illinois, U.S., Naturalization Index, 1926-1979 [database on-line]. Lehi, UT, USA: Ancestry.com Operations, Inc., 2017.Original data: Illinois, Northern District Naturalization Index, 1840 - 1950. Salt Lake City, Utah: FamilySearch, 2016.
About Northern District, Illinois, U.S., Naturalization Index, 1926-1979
This collection includes naturalization records from Illinois.
You can learn more about this collection at the FamilySearch website.