A Newspaper research can be time-consuming because not many papers are indexed online—but what a thrill it would be to find this ad!
You’d need to narrow the possibilities for which newspaper this could be, then locate repositories or online databases that carry the newspapers you want to search for the time period in question. One way to do this is searching the Illinois Newspaper Project online directory. Results show newspaper titles and years of publication; click the title to see repositories holding that publication.
If the papers you need are in a database such as NewsBank or ProQuest Historical Newspapers (available through many libraries), or GenealogyBank (by subscription), you’re in luck: Such databases use optical character recognition to search both articles and advertisements.
If the newspapers you need aren’t in an online database, you’ll have to visit the holding library to view it on microfilm, or ask your library to request the film through interlibrary loan.
To reduce your microfilm scrolling time, narrow the time period when you think the ad ran as much as possible. Try doing a Google search on terms such as Chicago boxing history. I came up with an interesting Encyclopedia of Chicago Web page—looks like boxing was a popular pastime in the Windy City. Browse local history books, too: You could find mention of the match your ancestor fought.
You may already have done this, but ask your relatives if they remember when this boxing match happened. (You might as well ask if they have copies of the ad, too.)
The February 2007 Family Tree Magazine has an article on finding and searching old newspapers—even those that aren’t indexed. Let us know if you find your ancestor’s ad!