There are BS exceptions - in the US "lascivious display of the genitals" - I believe that's wording - is illegal, so e.g. a photo of a girl with her feet behind her head is going to be a problem if you get caught.

Also close-ups of the genital region, even if they're clothed.

But simple nudes should never lead to anything, I'm not saying it's never happened in the United States of Insanity, or other similarly bad areas. I know it has happened.

The policy in the US seems to be permissive in terms of arrests, and it's up to the jury to decide whether it's CP or not. At least that was my understanding of the application of the law the last time I checked.

But if I was in the US and wanted to look at simple nudes I would. You can go into a bookstore and buy books of such photos.