I'm aware. But Puerto Rico is a commonwealth, so within the context of my post when I wrote "in the US", I was referring to the 50 states and the federal district. I apologize if it wasn't clear.
I found this incredibly obvious given your context.
Given the content of the rest of the post, did you really think the author was unaware of that?
Technically it's a possession and territory belonging to the of the United States, but not part of it.