You probably have no copyright claim. See United States District Court in BRIDGEMAN ART LIBRARY, LTD. v. COREL CORP., 36F. Supp. 2d 191 (S.D.N.Y., 1999), wherein it was found that:
“a copy in a new medium is copyrightable only where, as often but not always is the case, the copier makes some identifiable original contribution. In the words of the Privy Council in Interlogo AG, “there must . . . be some element of material alteration or embellishment which suffices to make the totality of the work an original work.”…“it is uncontested that Bridgeman’s images are substantially exact reproductions of public domain works, albeit in a different medium.”…There has been no suggestion that they vary significantly from the underlying works. In consequence, the change of medium is immaterial.”
The point is creative content. Although photographers and restoration people often claim otherwise, if your goal is to reproduce, maintain, or correct/clean up to such that the original creative content is preserved, then by definition you are not adding creative content. Copyright is not about enshrining work and effort, it’s about creative works.
This gets into all sorts of strange situations in the digital age. Someone goes to an art gallery and takes a photograph of a 300 year-old painting, trying to maintain the original creative content as accurately as possible. That is effort, skill, and work - but not adding new creativity. But that person will claim that the image they own is now their “copyright.” Then they’ll sell that to a book, and the book publisher will claim that this image - with no creative content added - is now “copyrighted.” Then someone out there will scan the book, make a JPG, and put it on their webserver, and claim they “own” the scan and it’s their “copyright.”* In all cases, no creativity is added, and in all cases, everyone thinks they have a copyrighted work.
So answering your questions:
“I know the maps are out of copyright for a long time. But now I have a issue. Do I own the work?” - you do not create a new copyright by slavish copying, or by doing things which do not add an identifiable creative contribution. So almost certainly, no.
“Is there a copyright now because to the restoration and photography work I did.” - almost certainly not.
“If I give them a digital copy of each map for records can they legally make copies of the maps.” - almost certainly, yes.
“Can I make my own copies of the maps? For myself, others? Can someone make a copy of my copies legally?” - almost certainly, yes.
“But I saved my work in layers. Each layer in PS is essentially a separate image. Are my layers copyrighted? Is this a loophole?” - almost certainly, not. The Bridgeman ruling noted that “the change of medium is immaterial”, which to me implies that it doesn’t matter how you save it, as long as you are not creating new creative content, then you have not created a new copyright.
The public domain is a great and wonderful thing. It means that at some point, the efforts of folks now exist not to make money for people, but to better mankind. In a way, your cleaning up these images is helping to better mankind, helping to preserve the works of the past creators of the maps. Don’t look at this as a lost opportunity just because you can’t lock away for 95 years these maps - I think you’d be surprised at how many people will buy copies of public domain works rather than just download them, if you package them properly and make them available. After all - Shakespeare has been in the public domain for hundreds of years, and anyone can download his works in a heartbeat. So why do books of his plays sell hundreds of thousands of copies, if not millions, yearly? Also note that this means you can use other public domain images to assist you. Imagine for example you have old maps of Civil War battlefields - you could put them into a book, with accompanying contemporary artworks, illustrations, and old photographs. You could include public domain text from innumerable published Civil War accounts. Just a couple ideas.
- And remember, just because a website says “all scans copyright me, me, me” doesn’t mean it’s true.