Do you ever notice that Americans say "I don't have" and Brits always say "I haven't got." Explain that one. I've also noticed that Britons never use "gotten." Americans still do. A retention of the Germanic ending that Great Britain dropped years ago? I think we also use "oxen" as the plural and I don't think British English does. I may be wrong .... Anyway, it's all very interesting to this English major (B.A., cum laude).
If you want to understand that kind of stuff, you have to go very carefully into the history of the language, the dialects, and the catchment areas for immigration to various parts of the US.
What is really relevant is what dialects were spoken in each English county, by each class, and where these groups typically migrated to in America. Of course, there were also Scots Gaelic speakers settling in the Carolinas, and Plattdeutsch speakers in Pennsylvania.