At creation US leaders were selected from a subsection of the population in all land governed by the nation. With Puerto Rico, DC, etc that’s no longer the case making the US an empire not a republic.
Controlling who has the vote has long been an issue, but denying political power to a region is a different category of thing than denying it to poor people etc.
Maybe, but then the US is a weird kind of reverse-empire, because it's exactly the capital where people don't get to vote, at least for the senate. An empire is usually where only people from the core region have any representation (if anyone does, because I don't think empires need to be democratic at all).
Controlling who has the vote has long been an issue, but denying political power to a region is a different category of thing than denying it to poor people etc.