Selling an article which has accompanying photos - copyright

If I sell a written article (eg an account of a trip) and have included photos with it, who retains the rights of the photos, if the magazine buys rights to the article?

US applicable advice only:
Normally the photographer retains copyright unless there is a document to state otherwise. However, publication rights should transition to magazine when you allow them to publish pictures, so you probably will not be able to sell copies of the pictures to other individuals, unless you retain this portion of the copyright in writing.

Note: you also need to register the images, otherwise I believe that if the publication registers the copy, you may automatically lose copyright in that case.

Just my take based on research, reading and not an informed opinion. See copyright lawyer for informed opinion.

Check your magazine contract. Even if they specify that they retain all rights, you might be able to get a waiver on it, so that you retain all rights (granting them a one time right to copy your images.) They would then have to contact you again for any reuse of the image.

Depending on the images, you may need release forms from the people in the photos. Again, check your contract.

Unless you're under contract to be their photographer I don't see why they should retain copyright forever from a single use.