We bought an 1857 Victorian home located on the bluff in Quincy, IL two blocks from the Mississippi river with Missouri on the other side. There are a few homes in town that have been proven to be part of the Underground Railroad, but I have no idea how they proved it.
When we bought the house, the previous owners pointed out an area in the basement (which is almost entirely original, with brick floors and all) that appears to have been a fairly good sized tunnel at some point. But that doesn't necessarily mean much, because Quincy has had lots of tunnels for lots of reasons. There used to be several breweries with tunnels that went all over town, for instance; and we had at least one prohibition bootlegger with his own system of tunnels. We know that the original owner of the home was the first banker in town, so he may have had his own reasons for having a tunnel. If it was a tunnel at all.
I recommend checking to see if your house is on the National Register of Historic Places, which is likely due to its age, condition, and the number of historic districts in town. The properties are also mapped here. Since the NR focuses on physical places, it may be helpful, but like all research it's a crapshoot based on who wrote the nomination and how long ago. Unfortunately it does not look like any of the record for Quincy have been digitized yet, so you would have to contact your State Historic Preservation Office to see where a paper copy is available. There may also be copies with the local library or government. I would try contacting the SHPO anyway, as some states in the area have Underground Railroad programs and initiatives.
Beyond that, the county historical society and local collections at the library are your best bet. Looking for references to the tunnel and the political persuasions of the banker-owner could yield something if you're willing to put in some time.The Eells House is recognized by the Park Service and listed on the Network To Freedom. Quincy was considered a stop, so it's plausible.
You might be able to get some help with this inquiry from the National Underground Railroad Freedom Center.
http://www.freedomcenter.org
That would be incredible!
We are not on the historic registry. Those are some great sites to check out in more depth. Thank you!