News From the Library of Congress:

Now available online at the Library of Congress website FREE a collection of Chicago Telephone Books. Why are these so important for your ancestor research? Because they include years beyond the available City Directory years! 1930’s, 1940’s, 1950’s, 1960’s and 1970’s.

The direct link to the Chicago Collection:

https://www.loc.gov/collections/united-states-telephone-directory-collection/?fa=location:illinois