This entry was originally written by Carol L. Maki and Michael John Neill for Red Book: American State, County, and Town Sources.
Although not a direct “port of entry” for American immigrants, many individuals regarded Illinois as their destination. County circuit courts in Illinois typically hold naturalization records prior to 1906; some of these are held by the Family History Library and the Illinois Regional Archives System. Early Cook County naturalization files were destroyed in the Chicago Fire of 1871. Numerous Illinois naturalization records are located at the National Archives—Great Lakes Region, 7358 S. Pulaski Rd., Chicago IL 60629; contact the Great Lakes Region for full particulars. Held by this repository is a Soundex index (Records of Immigration and Naturalization Service, Record Group 85) for naturalizations (1871–1950). The index includes several northern Illinois counties (Cook County for 1871–1906), which has been microfilmed by the Genealogical Society of Utah. For any naturalizations that took place in this District Court after 1959, see the United States District Court—Chicago, Naturalization, Rm. 2062, 219 S. Dearborn, Chicago, IL 60604. This court also maintains an index of all naturalizations in the court from 1871 to the present. Szucs’ work, listed in Background Sources above, contains information on specific naturalization records from Calumet City and Chicago Heights.