After researching our Kerr name for many years, my uncles recently took a Y-DNA test, which led us to the immigrant ancestor. It appears our line comes through one of this immigrants son's whose line is not very well documented. At least I now have a starting point in the US.

So my advice is that if you have males who will take the Y-DNA test, have them do so. It may give you a starting point or help pinpoint where to look.