American citizens can apply for a passport card at the same time they apply for a passport book. There’s even a small discount when you do so.
I’ve heard, however, it’s better to apply for them separately because if you apply at the same time, both the book and the card will have the same number and if you lose one of them, the other becomes invalid when you report the loss. For example, this comment in this article below:
One important trick... do not get your card at the same time as the passport book. If you do that they will both have the same number and if one is lost or stolen, the other immediately becomes invalid. If you get the card separately it will have its own distinct number and will remain valid even if your passport book is stolen. Comment on thread in Elliot.org
Is this really the case? This seems really another reason not to get the card — or at least not to get the card at the same time.