After working recently on another line for my daughter, I stumbled upon a WorldConnect database that had quite a bit of information on the Kahre family. I posted a "Post-Em" but have not received a reply. Much of the information appears to have come from a book entitled "The Kahre Connection" by J. Elwyn Kahre. A Google search turned up the title on Amazon.com but it was listed as unavailable.
My daughter's maternal 4th-great grandmother was Anna Maria Louisa Catherine Kahre, born April 25, 1840 in Kummerdingsen, Westphalia and died October 11, 1915 in Evansville, Vanderburgh Co., IN. She was the daughter of Heinrich Wilhelm and Marie Caroline Wilhelmina (Korff) Kahre. She married Karl Louis/Ludwig Ritt on July 28, 1864 in Vanderburgh Co., IN.
I will take the information from this database with a grain of salt, but it does give quite a few interesting clues - and traces the Kahre line back into the late 1690's.