Digital Past, which I found at the North Suburban Library System in Illinois, has a superb collection of digital documents. It's a little difficult to figure ouot at first because they don't show a list if the specific collections. But don't let this deter you. With a little exploring, it didn't take me long to find a system that worked for me. Searches a massive collection of photographs, postcards, diaries, oral histories, documents, movies, interpretive exhibits, and other historical materials from libraries, archives, museums, and other cultural venues throughout Illinois.
I suggest that if you are in search of a particular family line, start by browsing with a Proper Names. If you know a particular company or organization that plays a role in your family line, then browse by Organization, followed by a particular City if you know where the family lived in Illinois.
Here's the link: