All US charts (unless derived form British charts) are, as they say, in the public domain. That means they can be copied and reproduced. You will find chart books in USA of the Chesapeake Bay for instance reasonably chaeply developed from that source. Or, if you are sailing via the Canaries you will pick up all you need there - pilot books and all!
Or, again, there is an outfit that sells second hand charts advertising in the classiifeds of YM, something like chartsales. There are good. Finally, there is an American company based on West coast which sells (legal) copies of slightly reduced in size, US charts - see the ads again.