You'll notice that Section 1 of the 18th Amendment and Section 2 of the 21st both reference territories in addition to states. The 21st goes a little further, calling out "Possessions" as well, making this sound like some kind of demon Sam and Dean Winchester are going to have to deal with.

This is just a reminder that the government of the United States does in fact have territories that aren't states. Places like Puerto Rico, Guam, and American Samoa are governed by the United States but don't have representation in Congress.