By pure chance, I found out there was a Plan red for the event of war between the states and Britain. The plan was conceived in the late 20s and early 30s of the previous century. It seems the article makes no mention of the expected reasons for such a war.
Initially I assumed it was customary to plan for the event of war with any serious rival - particularly since there were a series of Colour Plans for various war theatres. But the plan was classified until 1974, which seems to indicate it was not expected there would be such a plan.
So, did the United States expect war against Britain and why?
Wikipedia further states the following, which I don't know how to assess, but which seems important:
War Plan Red was developed by the United States Army following the 1927 Geneva Naval Conference and approved in May 1930 by Secretary of War Patrick J. Hurley and Secretary of Navy Charles Francis Adams III and updated in 1934–35; it was not presented for presidential or Congressional approval. Only the United States Congress has the power to declare war.