My gr. grandmother was Margaret Raetz, born in Detroit in 1870. Her father was Michael Raetz born in Gehlenberg, Germany Dec. 4, 1833. His parents were Jacob Raetz and Susana Muller. Believe the original spelling was Ratz, with an umlaut over the "a", but I have seen so many variations on it, nothing would surprise me. Gehlenberg is near Cologne and I found some records pertaining to my family thru LDS films for Kelberg parish. In my research thru Catholic registers here in Detroit, I also noticed a Raetz/Roths/Raths line from Luxembourg. I'm sure there are many more locations, but maybe this will set someone on the right track.