[Areading314]

OK people, the definition of empire is this:

From merriam-webster:

1 a

(1) : a major political unit having a territory of great extent or a number of territories or peoples under a single sovereign authority; especially : one having an emperor as chief of state

(2) : the territory of such a political unit

b : something resembling a political empire; especially : an extensive territory or enterprise under single domination or control

2 : imperial sovereignty, rule, or dominion

3 capitalized [Empire State, nickname for New York] : a juicy apple with dark red skin that is a cross between a McIntosh apple and a Red Delicious apple

Since the US does not have a single authority controlling it (i.e. "is a democracy") it cannot be an empire. They are mutually exclusive according to the dictionary.