E-mail: Ask the State Library.
- Illinois State Library
Gwendolyn Brooks Building
300 South 2nd Street
Springfield, IL 62701-1796
Telephone: 217-785-5600, or 800-665-5576 (Illinois Residents)
Hours and holidays: Mon. - Fri. 8:00 am - 4:30 pm. Closed on official Illinois holidays.
Map, directions, parking, and public transportation:
Internet sites and databases:
- Illinois State Library services for libraries, the public, state employees, about the library, digital archives, veterans history, catalogs, literacy, maps, research databases, library card application.
- Illinois State Library Catalog online by keyword, title, author, subject, or ISBN/ISSN. Also available in WorldCat.
- Genealogical Resources census, military, county histories, atlases, genealogy, history, and Internet resources.
- Research Databases by book, magazine, or subject area.
The Illinois State Library collects official publications of the state and federal governments. This includes territorial, state, and federal censuses 1810-1930, county plat books and atlases, Illinois county histories, Sanborn fire insurance maps, the Draper Manuscript Collection, Revolutionary War pensions and bounty land warrants, and other military records from the Black Hawk War, Mexican War, and American Civil War muster rolls, and veterans' burials in Illinois 1774-1898. 
The State Library also has seven public Internet-connected computers for genealogists, as well as a Wi-Fi connection for wireless users.
If you cannot visit or find a source at the Illinois State Library, a similar source may be available at one of the following.
- National Archives I, Washington DC, census, pre-WWI military service & pensions, passenger lists, naturalizations, passports, federal bounty land, homesteads, bankruptcy, ethnic sources, prisons, and federal employees.
- Allen County Public Library, Fort Wayne, Indiana, premier periodical collection, including Midwestern genealogies, local histories, databases, military, censuses, directories, and passenger lists.
- National Archives at Chicago old federal court and agency records for Illinois and Midwest U.S. federal censuses 1790–1940; military service and pension indexes, passenger lists, naturalizations, Ancestry.com, HeritageQuest, Fold3.
- Newberry Library, Chicago, a large repository with genealogies, local histories, censuses, military, land, indexes, vital records, court, and tax records mostly from the Mississippi Valley, eastern seaboard, Canada, and the British Isles.
- Illinois State Archives, Springfield, county/state records, pre-Chicago fire sources, indexed vital records, early land grants, military records, all fed/state censuses, surname card index.
- Illinois Regional Archives Depository (IRAD), Springfield, HQ of 7 regional archives of local Illinois county/town records: birth, marriage, death, land, tax, voting reg., probate, naturalization, civil & criminal court, coroner, poorhouse, jail. For Sangamon County see IRAD-University of Illinois at Springfield.
- University of Illinois at Urbana-Champaign Main Library one of the best book collections in America, including county histories, and farmers registers. Think of it as another archives for Illinois.
- Sangamon County Clerk births, marriages, deaths.
- Sangamon County Historical Society educational programs, historic buildings, and museums.
- Sangamon County Circuit Court Clerk divorce, probate, court, and naturalizations.
- Sangamon County Recorder land records.
- Sangamon County Coroner suspicious or unusual deaths.
- U.S. District Court, Central District of Illinois recent civil and criminal cases.
- Illinois Dept. of Health Vital Records, Springfield, birth, marriage, death, adoption, and divorces.
- Illinois State Genealogical Society, Springfield, research guidance, teaching via webinars and the ISGS blog for free, death certificates 1916-1947 for a fee. No research requests.
- Abraham Lincoln Presidential Library and Museum, Springfield, genealogy, plat maps, atlases, oral and county history, cemeteries, census, vital records, naturalizations in many counties.
- Lincoln Library, Springfield, indexed obituaries, city directories, the Sangamon Valley Collection has photos, yearbooks, histories, and maps for studying Sangamon and surrounding counties.
- Repositories in surrounding counties: in Illinois: Cass, Christian, Logan, Macon, Macoupin, Menard, Montgomery, and Morgan.
- Arlington Heights Memorial Library a huge collection, with printed genealogies, manuscripts, periodicals, newspapers, special aids, surname folders—a great overall genealogy collection.
- Chicago History Museum 20 million manuscripts, letters, certificates, diaries, genealogy charts, log books, journals, memoirs, minutes, muster rolls, scrapbooks, sermons, speeches, and telegrams.
- Chicago Title and Trust for a fee they will search property records prior to the Chicago fire.
- John A. Logan College Library, Carterville, this library is a focal point of Southern Illinois genealogy. Their collection is huge.
- Peoria Public Library enjoys a large genealogy and local history department, including many indexes, DAR files, and basic genealogy resources for the plains states.
- Pritzker Military Museum and Library, Chicago, 45,000 military history books, unit histories, photos, uniforms, equipment, insignia, and ships of many world militaries. They help genealogists.
- South Suburban Genealogical and Historical Society, Hazel Crest, a very good collection with local histories, genealogies, naturalizations, Pullman Car Works personnel, obituaries, church histories.
- Southern Illinois University at Edwardsville Lovejoy Library best library in southern IL with a large genealogical collection of newspapers, biographies, county histories, family folders, and maps.
- Swenson Swedish Immigration Research Center, Rock Island, IL, Swedish church records, census, passenger lists, lodges, newspapers, directories.
- University of Chicago Library plentiful historical records, including Durrett Collection of historical Kentucky and Ohio River Valley manuscripts of early people in the Ohio Valley.
- Urbana Free Library their strength is Champaign County history, but they have good basic genealogy for the entire United States including printed genealogies, manuscripts, family folders.
- Asher Library, Chicago, Spertus Institute for Jewish Studies 500,000 books, and films.
- Brethren Historical Library and Archives, Elgin, IL, cultural, socio-economic, theological, genealogical, and institutional history of the Brethren.
- Evangelical Lutheran Church in America Archives, Elk Grove Village, IL, serves historians, congregations, synods, genealogists and others interested in Lutheran history.
- Roman Catholic Archdiocese of Chicago Archives parish records, priest biographies, sacramental, school, or orphanage records.
- Repositories in surrounding states: Indiana, Iowa, Kentucky, Michigan, Missouri, and Wisconsin
- National Personnel Records Center (NPRC), St. Louis, MO, military and civil services personnel records. For servicemen and servicewomen discharged from 1912 to 1953. 
- Polish Genealogical Society of America, Milwaukee, WI, 60,000 books on Polish history, art, culture, and reference.