Available federal census for Illinois begins with 1820. (The exception is Randolph County, for which the 1810 census survived.) Mortality schedules exist for 1850, 1860, 1870 (partial), and 1880. Various territorial and state censuses exist, as well. The 1810, 1818, and 1820 territorial censuses have been indexed and published. State censuses for 1825, 1835, 1845, 1855, and 1865 are at the Illinois State Archives and on subscription site Ancestry.com, but many counties are missing or incomplete for the censuses through 1845.
Illinois county-level court records include probate, civil, and criminal cases, divorce, adoption, naturalizations and guardianship. The records are held by the clerks of the county court and the circuit court for each county. Older court and vital records are often available on microfilm through the Family History Library (FHL), or may have been transferred to an Illinois Regional Archives Depository (IRAD) location.
Illinois law required the filing of vital records beginning in 1877, but statewide registration didn’t begin until 1916. Compliance wasn’t always immediate. Post-1916 birth and death records are available from the State Department of Public Health in Springfield. Earlier records (sometimes including pre-1877 records) can be obtained from the county clerk.
Marriages are all at the county level. For divorces, a statewide index exists only from 1962. Pre-1877 marriage records provide little information. But in 1877, preprinted marriage books included columns for such details as ages, residences, birthplaces, and often the names of the parents of the bride and groom. Couples were required to obtain a marriage license, and marriage returns filed by the minister or justice of the peace indicated where the marriage took place and may provide the couple’s religious denomination. Divorce records are part of the civil court records at the county level.
In 1871, the Great Chicago Fire destroyed much of the city and its local records. This makes thorough research in alternate records important for those with early Chicago ancestors. A helpful guide for locating such records is Chicago and Cook County: Guide to Research by Loretto Dennis Szucs.
Another useful statewide resource provided by the Illinois State Genealogical Society is their Cemetery Location Project. It is available online at http://rootsweb.ancestry.com/~ilsgs/ilcemetery.html The Illinois USGen web site includes a county-by-county list of cemeteries, as well as an index to tombstone transcriptions and abstracts.
Church records can provide vital information. Sacramental records to 1915 for the Roman Catholic Archdiocese of Chicago are available through the FHL. The Evangelical Lutheran Church in America Archives in Chicago is the central archive for American Lutheran Church records research.
Online help for Illinois research is abundant. The Illinois State Archives and the Illinois State Genealogical Society have worked for years to compile the Illinois Marriage Records Index, 1763-1900. The most up-to-date edition of this enormous ongoing project is available at http://cyberdriveillinois.com/departments/archives/marriage.html. The State Archives also provides two online indexes to death records: The index to death certificates from 1916 to 1950 is at http://sos.state.il.us/departments/archives/idphdeathindex.html. The pre-1916 Statewide Death Index is at http://os.state.il.us/departments/archives/death.html.
Many 19th- and early 20th-century Chicago immigrants later migrated farther west. The FHL’s strong microfilm holdings for Chicago and Cook County ease the burden of big-city research. Chicago vital records begin in 1871 and include births to 1933, deaths to 1945, and marriages to 1920. Chicago voting records, which can serve as a substitute for the missing 1890 census, are indexed for 1888, 1888 to 1890, and 1892. The Chicago Historical Society is also an important resource for those with ancestors from the Chicago area.
The Illinois State Historical Library has a biographical index of more than 10,000 Illinois individuals in local histories and other sources. The Newberry Library is a private library in downtown Chicago with extensive reference materials and special collections for Illinois and beyond.
The IRAD system houses older county and local government records at seven regional archives, located at various Illinois university campuses. The website, http://cyberdriveillinois.com/departments/archives/irad/iradhome.html, provides a searchable database of the records available at each IRAD location, as well as a county-by-county listing.
- The Illinois Military Tract; a Study of Land Occupation, Utilization, and Tenure by Theodore Leonard Carlson (University of Illinois Press, 1951)
- Original Land Grants, 1824-1870 compiled by Charla Murphy et al. (Williamson County Historical Society, 1997)
- Record of the Services of Illinois Soldiers in the Black Hawk War, 1831-32, and in the Mexican War, 1846-48 prepared by Issac H. Elliott (H.W. Rokker, State Printer, 1882)
- War of 1812 Bounty Lands in Illinois indexed by James D. Walker with an introduction by Lowell M. Volkel (Heritage House, 1977)
- Counties of Illinois compiled by Edward J. Hughes (E.J. Hughes, 1941)
- County and Township Gazetteer; Notes on the Location of Illinois County Seats compiled by Sheila Kelly, notes by Lori Lovett (Illinois State Archives, 1988)
- A Gazetteer of the States of Illinois and Missouri by Lewis C. Beck (C.R. and G. Webster, 1823)
- Illinois Atlas and Gazetteer (DeLorme Mapping Company, ca. 1991)
- Illinois Place Names compiled by James N. Adams, edited by William E. Keller with an addendum by Lowell M. Volkel (Illinois State Historical Society, 1989)
- Indian Place Names in Illinois by Virgil Vogel Jr. (1963)
- Maps of Illinois Counties in 1876, Together with the Plat of Chicago and other Cities (Mayhill Publications, 1972)
- Origin and Evolution of Illinois Counties by Jessie White, Secretary of State (The State, 2000)
- Biographical Sketches of Illinois Officers Engaged in the War Against the Rebellion of 1861 by James Grant Wilson (J. Barnet, 1862)
- Fighting Men of Illinois edited by Publishers Subscription Co. (W.C. Cox, 1974)
- Illinois in the Civil War, 2nd edition by Victor Hicken, foreword by E.B. Long (University of Illinois Press, ca. 1991)
- Illinois Soldier’s and Sailor’s Home at Quincy, 2 vols., indexed by Lowell M. Volkel (Heritage House, 1975-1980)
- Index to War of 1812 Pension Files, revised edition, 2 vols., transcribed by Virgil D. White (National Historical Publishing Co., 1992)
- The Martyrs and Heroes of Illinois in the Great Rebellion, edited by James Barnet (Press of J. Barnet, 1865)
- Record of the Service of Illinois Soldiers in the Black Hawk War, 1831-32, and the Mexican War, 1846-48 by the Illinois Military and Naval Department (H.W. Rokker, State printer, 1882)
- Remembering Illinois Veterans (Illinois State Archives, 1992)
- Report of the Adjutant General of the State of Illinois, 9 vols. revised by J. N. Reece (Phillips Brothers, 1900-1902)
- Revolutionary Soldiers buried in Illinois by Harriett J. Walker (Genealogical Publishing Co., 1967)
- Soldiers of the American Revolution Buried in Illinois (Illinois State Genealogical Society, 1976)
- The Bench and Bar of Illinois: Historical and Reminiscent, 2 vols., edited by John M. Palmer (Lewis Publishing, 1899)
- The Illinois Fact Book and Historical Almanac, 1673-1968 by John Clayton (Southern Illinois University Press, 1970)
- 1850 Illinois Mortality Schedule, 3 vols. transcribed by Lowell M. Volkel (1972-ca. 1973)
- 1860 Illinois Mortality Schedule, 3 vols. transcribed by Lowell M. Volkel (Heritage House, ca. 1979)
- The Era of the Civil War: 1848-1870 by Arthur Charles Cole, introduction by John Y. Simon (University of Illinois Press, ca. 1987)
- Guide to Public Vital Statistics Records in Illinois prepared by Illinois Historical Records Survey (Heritage House, 1976)
- Index of Illinois Marriages, earliest to 1900, CD-ROMs (Illinois State Genealogical Society)
- Marriages from Illinois Counties, 6 vols., by Walter R. Sanders (W.R. Sanders, 1976)
- Vital Records from Chicago Newspapers compiled by the Newspaper Research Committee, Mrs. Edward Rickie, Chairman (Chicago Genealogical Society, 1971-1981