It is indeed an empire. Two good books:

[1] How to Hide an Empire: A History of the Greater United States by Daniel Immerwahr https://www.amazon.com/How-Hide-Empire-History-Greater/dp/03...

[2] Understanding Power by Noam Chomsky https://www.amazon.com/Understanding-Power-Indispensible-Cho...

Yes, generally that is true. There are a few words, at least out west, that stand out: "About" "Schedule" "America".

The last one is in jest. The word is pronounced the same--in the US, often the US is called America, seemingly excluding Canada, Central America, South America.

And a fact that I didn't know until recently was that the Philippines prior to WW II was part of the United States. See "How to hide an empire" by Daniel Immerwahr: https://www.amazon.com/How-Hide-Empire-History-Greater/dp/03...

There's a great book by Daniel Immerwahr on the subject: How to Hide an Empire (https://www.amazon.com/How-Hide-Empire-History-Greater/dp/03...).