Since I am a professional genealogist I can give you some ideas about where to look.If you live in Wisconsin, I suggest, you visit the Ozaukee County Court House and see if he immigration and naturalization papers are there.This may not help much, but sometimes they are hidden gems.Be very careful about the location cited on the naturalization papers.My greatgrandfather listed the King of Bavaria as his former soveriegn.The Rheinland Pfalz where he lived was at the time controlled by Bavaria. The other thing is if you know where she died, find her death certificate and see what is listed as country of birth. Be advised that although Ozaukee County still maintains many such records, older records (1876 back) are also maintained at the nearest UW campus, which in this case is probably Milwaukee.They need to be looked at too. Last but probably best, is to check out the Mormon Church Family History Center nearest you.They are always listed in the phone book.They have the largest genealogical database in the world and you do not have to be a Mormon to use it. If you live in the Port area, Sheboygan is the nearest location.I believe West Allis has one two. If you should find out where she came from and want some help searching German records, I will be happy to help.There is a small problem here though in that some Postels are catholic and I do not read Latin, only German. As for the origin of Postel's at least in my ancestral area, they came from Switzerland, near Berne.