I had a hard time figuring this one out until I read some other posts. Then I had lots of ideas.
But the first thing that occurred to me was the Clinton IA Public Library Root Cellar. My Irish immigrant ancestors settled in Clinton Co., IA. I've made a couple of trips across Illinois to visit this library and go down in the basement to the Root Cellar. It has been a tremendous resource in discovering details about my Kain and Kennedy ancestors. It was there that my wife and I learned about the possibility of the crossing of paths of my great-great-grandfather, John Kennedy, and her grandfather, Albert Crowe. I have a long list of resources to check there the next time I find time to cross the Mississippi River into Iowa. The Root Cellar librarians are very knowledgeable and helpful. I wish I lived even closer so I could spend more time there.