William A. Henderson/IL/VA/WV

I've hit a brick wall on my great grandfather Wm. A. Henderson.Info on his marriage license stated he was born 1848 in West Virginia.However, WV did not become a state until 1861.Therefore, I am assuming he was born in a VA county which later acame the state of WV.His parents were listed as James Henderson & Margaret Thomas on the marriage license in Illinois.He was 52 and stated it was his 1st marriage, which I find hard to believe.His bride, Myra McKinney-O'Riley-Rabbit-Henderson was 41 and had been married twice before (both husbands died).Her death certificate listed her as married at time of her death in Oct 1917.I can find no death certificate in the county where he lived or surrounding counties either for 1917 or later.A family story (not confirmed) said he donated his body to science.I checked but found no record of that either.William's daughter was my grandmother.Whenever I asked questions about family, she was very secretive.I would greatly appreciate any help or suggestions.Thanks!