|Publication: The Quincy Daily Whig; Date: Jan 18, 1890; digital image, Quincy Historical Newspaper Archive, Quincy [Illinois] Public Library Website, www.quincylibrary.org, accessed 2 January 2013|
Consider searching for your "missing" ancestors in the newspaper. Perhaps someone advertised for information on their whereabouts and perhaps they were missing to their contemporary relatives as well.
I have a cousin, Arsulus Rampley who "went missing" in the 1920s and was never located. A court case in the 1940s referenced his disappearance and declared him legally dead, but I've never conducted newspaper searches to see if there is any mention of him. With that unusual name, locating references (if any were published) should not be too difficult and perhaps I should do that.