Genealogy

Researching family history using Illinois county records connects researchers to one of the most geographically and demographically significant states in American genealogy. Illinois became a state in 1818 and experienced rapid population growth through the mid-19th century as migrants from Kentucky, Tennessee, Ohio, and the Mid-Atlantic states settled the prairies, followed by massive immigration from Germany, Ireland, Scandinavia, and Southern and Eastern Europe through the late 19th and early 20th centuries. Chicago’s Cook County became one of the most populous counties in the United States and one of the most genealogically rich, while the remaining 101 Illinois counties document the agricultural communities and small-town life of interior America. This guide explains how to research family history using Illinois county records, which record types are most productive, and where to find the records.

Illinois Circuit Court Records for Genealogy

Illinois’s Circuit Court is the primary trial court in each county and generates the probate, civil, and criminal records most useful for genealogical research.

Illinois probate records: Illinois probate proceedings are administered by the Circuit Court in each county. Illinois probate records include the will or intestacy petition, the inventory of estate assets, the final account of administration, and the distribution order showing which heirs received which assets. The distribution order frequently identifies children with their married names and addresses at the time of the estate settlement, providing a genealogically valuable snapshot of a family’s composition and geographic dispersal.

Illinois Circuit Court naturalization records: Illinois Circuit Courts processed naturalization declarations and petitions before federal courts assumed exclusive jurisdiction in 1906. Illinois Circuit Court naturalization records from the late 19th century are among the most important genealogical sources for the state’s large immigrant population. These records often contain the applicant’s country of birth, date and port of arrival, age, and the names of witnesses who could vouch for the applicant’s good character.

Cook County Circuit Court: Cook County’s Circuit Court holds the most voluminous court records in Illinois, reflecting Chicago’s status as the largest city in the Midwest and the destination for millions of immigrants from the late 19th century onward. Cook County Circuit Court probate records, naturalization records, and civil case files collectively document the Chicago immigrant community in extraordinary detail.

Illinois divorce records: Illinois divorce proceedings in the Circuit Court generated detailed case files that document the parties’ circumstances, the grounds for divorce alleged, and in contested cases the testimony of witnesses about the parties’ conduct and history. 19th-century Illinois divorce petitions may include prior residency information, marriage dates, and biographical detail about the parties that supplements vital records.

Illinois Land Records for Genealogical Research

Illinois land records document the settlement of the state from federal public land distribution through private transactions across 102 counties.

Federal land entry records for Illinois: Illinois public land was distributed under the Public Land Survey System beginning in the early 19th century. The Bureau of Land Management’s GLO Records portal at glorecords.blm.gov provides free access to Illinois federal land entry records including homestead patents, cash entries, and military bounty land warrants. These original federal land records document the first acquisition of Illinois public land and are searchable by the grantee’s name.

Illinois County Recorder deed records: Each Illinois county’s Recorder of Deeds maintains deed records from the county’s organization through the present. Illinois deed records from the 19th century document land transactions that trace family land holdings across generations, identify neighbors and business associates, and in some cases include recitals of family relationships when land was transferred within families.

Illinois Military Tract: A large tract of Illinois land in the western part of the state, bounded by the Illinois and Mississippi Rivers, was reserved for veterans of the War of 1812 as military bounty land. This Military Tract generated a distinctive set of land records documenting veterans who received warrants that they or their assignees redeemed for Illinois land. Researchers with War of 1812 veteran ancestors in their family lines should investigate Illinois Military Tract records as a potential source for Illinois connections.

Chicago and Cook County Genealogical Resources

Cook County’s Chicago encompasses the most genealogically rich urban record environment in the Midwest, with resources at multiple institutions supplementing the official county records.

Newberry Library: The Newberry Library at newberry.org in Chicago is one of the premier genealogical research libraries in the United States. The Newberry holds extensive collections of Illinois county histories, family genealogies, newspaper collections, and primary sources covering Illinois and the broader Midwest. The Newberry’s genealogy collection is particularly strong for Chicago immigrant communities and Illinois military records.

Chicago History Museum: The Chicago History Museum at chicagohistory.org holds primary source collections documenting Chicago’s history from the early 19th century, including photograph collections, manuscript collections, and historical records that supplement official county records for Chicago ancestry research.

Illinois Regional Archives Depositories (IRAD): Illinois has established a system of Regional Archives Depositories at universities across the state to hold transferred county government records. The Illinois State Archives at ilsos.gov/departments/archives coordinates the IRAD system, and researchers can identify which records from specific Illinois counties are held at IRAD facilities versus still held by the county.

Chicago Foreign Language Press Survey: The Chicago Foreign Language Press Survey, a WPA project from the late 1930s, abstracted articles from Chicago’s immigrant language newspapers covering genealogically relevant topics including immigration, community history, and notable individuals. The survey translations are accessible through the Newberry Library and provide access to the immigrant community press for genealogical context.

Illinois Vital Records for Genealogical Research

Illinois vital records history creates specific challenges and opportunities for genealogical researchers working with Illinois ancestry.

Illinois vital registration history: Illinois enacted a statewide vital registration law in 1877 requiring registration of births and deaths, though enforcement and completeness improved gradually over subsequent decades. Cook County’s registration is generally more complete from earlier in this period than many downstate counties. For births and deaths before 1877 and for unregistered events after 1877, researchers must rely on church records, cemetery records, and county court records as alternative sources.

Illinois Department of Public Health Vital Records: The Illinois Department of Public Health maintains statewide vital records from January 1, 1916 for deaths and from 1916 onward for births and marriages in centralized form. Earlier records may be held by the county clerk or at IRAD facilities. The Illinois State Archives Death Certificate Index covering 1916 to 1950 is searchable online and provides name, date, county, and certificate number for each entry.

Cook County and Chicago vital records: Cook County’s vital records from the late 19th century onward are among the most complete for any large Illinois county. The Cook County Clerk maintains historical vital records accessible through the county’s vital records office and through FamilySearch indexes covering Cook County births, marriages, and deaths from the 19th century.

German and Scandinavian church records: For Illinois’s large German and Scandinavian immigrant communities, church records are essential genealogical sources covering the period before civil registration was reliable. Lutheran, Catholic, Methodist, and other denominational church records from Illinois immigrant communities document baptisms, marriages, and burials in communities that maintained separate ethnic religious institutions for decades after immigration. Many Illinois church records have been microfilmed by FamilySearch.

For more on Illinois county records and genealogical resources, see the Illinois county records guide. For general guidance on genealogical research, see How to Use County Records for Family History and Vital Records for Genealogy Research.

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Illinois Census Records for Genealogy

Illinois census records supplement county records by documenting Illinois ancestors at ten-year federal census intervals, with state census enumerations providing additional coverage.

Illinois in the federal census: Illinois first appeared in the federal census in 1820, documenting an early settler population of roughly 55,000. The Illinois population grew explosively through the mid-19th century as the Illinois and Michigan Canal, the Illinois Central Railroad, and Chicago’s emergence as a regional hub attracted migrants from across the country and immigrants from Europe. The 1850 through 1880 federal census records are particularly productive for Illinois research because they document the first and second immigrant generations before Chicago’s great demographic expansion.

Illinois state census of 1855 and 1865: Illinois conducted state census enumerations in 1855 and 1865, providing population data in the intervals between federal census years during a critical period of Illinois settlement. The 1855 Illinois state census is particularly valuable because it captures the Illinois population at mid-decade between the 1850 and 1860 federal enumerations and documents many families that moved through Illinois in transit to points further west. The Illinois State Archives holds surviving schedules from the Illinois state censuses.

Cook County and Chicago directories: For Chicago ancestors between census years, annual Chicago city directories from the mid-19th century onward document heads of household by name, occupation, and address. The Chicago city directories, accessible through the Newberry Library and digitized on Ancestry.com, provide year-by-year documentation of Chicago residents that supplements decade-interval census records.

Illinois Genealogical Research Organizations

Illinois’s rich genealogical record environment has produced specialized organizations and collections that supplement official county records.

Illinois State Genealogical Society: The Illinois State Genealogical Society at ilgensoc.org publishes the Illinois State Genealogical Society Quarterly and maintains indexes to Illinois vital records, cemetery records, and other genealogical sources compiled by society members. Their database of Illinois genealogical resources is searchable online and provides finding aids to county-level records across all 102 Illinois counties.

Midwest Genealogy Center: The Midwest Genealogy Center at mymcpl.org in Independence, Missouri is the largest freestanding genealogy library in the United States and holds extensive collections for Illinois and the broader Midwest region. While located in Missouri, the center’s Illinois holdings including county histories, microfilmed records, and published indexes make it a significant resource for Illinois genealogical research.

FamilySearch Illinois collections: FamilySearch has digitized extensive Illinois genealogical records including Cook County vital records, Illinois county deed records, Illinois Probate Court records, and naturalization records from Illinois courts. These free online collections make Illinois one of the better-covered states for online genealogical research, particularly for the 19th and early 20th centuries that represent the peak of Illinois’s immigrant settlement period.

Illinois county histories and biographical encyclopedias: Illinois’s 102 counties produced an extraordinary volume of county histories and biographical encyclopedias during the 1870s through 1900s, documenting prominent citizens with biographical sketches that include birthplace, parentage, migration history, and family details. These county histories are a standard starting point for Illinois genealogical research and are accessible through the Newberry Library, the Illinois State Library, and in digitized form through the Internet Archive at archive.org and through subscription databases including Ancestry.com. For researchers with Illinois ancestry, checking the county history for the ancestor’s county of residence frequently reveals biographical detail that supplements official county records.