Chronicling America: Historic American Newspapers:
https://chroniclingamerica.loc.gov/

Digital Research Library of Illinois History:
http://livinghistoryofillinois.com/

Explore Chicago Collections:
https://explore.chicagocollections.org

Family Search:
https://familysearch.org

Find A Grave:
https://www.findagrave.com

Genealogy Online: Historical Cook County, Illinois Vital Records:
https://genealogy.cookcountyclerk.com

Illinois Digital Archives
Illinois Digital Archives (other historical photos and documents from the area)

Illinois State Archives:
http://www.cyberdriveillinois.com/departments/archives/home.html

Lake County IL Genealogical Society:
http://lakecountyilgenealogy.org/

Library of Congress National Screening Room:
https://www.loc.gov/collections/national-screening-room/

Linkpendium Genealogy and Family History:
https://www.linkpendium.com/

National Archives:
https://www.archives.gov/research/genealogy

The Newberry:
http://www.newberry.org/genealogy-and-local-history

Tax Rolls for Cook County:
http://www.cookcountypropertyinfo.com/

Tax Rolls for Kane County:
http://www.kanecountyassessments.org/Publications.html
http://kaneil.devnetwedge.com

Tax Rolls for Lake County:
https://www.lakecountyil.gov/388/Assessment-Lists
https://maps.lakecountyil.gov/mapsonline/

Tax Rolls for McHenry County:
https://www.co.mchenry.il.us/county-government/departments-a-i/assessments/assessment-rolls