This is the tenth amendment to the constitution:
The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people.
The United States is different and separate from the original 13 states and the current 50 states. The original 13 states agreed to create a separate entity called United States, to manage specific goals shared by the 13 states.
The 13 states did not combine and become the United States. The states are separate from each other and separate from United States.
Geographically, the land of the United States is simply the District of Columbia and other lands throughout the states belonging to United States, plus islands such as Guam.
What is present-day Germany used to be a collection of smaller states or cities. They eventually combined, not necessarily with consent, to become one entity called Germany. They areas within Germany are part of Germany not separate from Germany. Or maybe we all are incorrect about Germany as well!
The United Nations is an intergovernmental organization with 193 member states. The member states are still sovereign. No one believes there is just one country called United Nations. For the same reason, United States is really an intergovernmental entity with 50 member states. That’s at least the way I see it.
It might help to leave out “the” when talking about United States. One might say the plane left Peru and arrived in Panama. One would not say the plane left the Peru and arrived in the Panama. Therefore, we could say the plane left United States and arrived in Peru.
If I were to say that I drove across the United States, that would really be impossible, since the United States is D.C. and land scattered across the fifty states. Driving across United States would really mean driving from one end of District of Columbia to the other. 🙂
There may be more to study. Should United States be called United States of America? Is there a difference between United States and United States of America? Not sure.