Work on my wife's family in Chicago has been challenging. The reasons are many. My one brick wall in Chicago, is a William Frame (aka William Apgar) born in Chicago in the 1880s, the son of English immigrants. For reasons that are unclear, he takes the name Apgar at the time of his marriage in 1909. This name has no significance in his family whatsoever.
A while back we posted an article where I outlined my "proof" that a 1910 census enumeration for William Frame is actually that of William Apgar. It shows how I outlined my case and organized the details to see if my conclusion was correct. Based upon what I knew then (and what I know now) I know I have the right person.
Of course, the problem is that William Frame/William Apgar disappears around 1918 and is never heard from again.