Unless copyright law has changed since then, the circle c doesn't matter. The way copyright works in the US, the rights to any creative work are automatically reserved for the author.
I'm not an expert in copyright law by any means. I only recall the story I heard when the man who put the copyright information on the paper released a book a couple of years ago. I'm forgetting his name at the moment.
This did in fact change since King's time. IIRC, what you say is true only after the adoption of the Berne convention in 1988.
That changed around 1989 with the Berne convention to be the way you describe.