Before the Civil War, the states were all separate. People used to say "United States are". Wasn't until the war ended, people started saying "The United States is". Under Lincoln, we became one nation.
Nicolas Cage - Ben Gates

“As the President of the United States, this comes with the full weight, power and authority of my office. Fuck you.”

Jamie Foxx - President Sawyer

“- Raphelson: You can't do this! I am still the President of the United States!
- President Sawyer: Then consider this a coup d'état!”
Richard Jenkins - Raphelson
Jamie Foxx - President Sawyer

“- Mission Control: President's calling, Buckaroo.
- Buckaroo Banzai: The president of what?
- Mission Control: The president of the United States.
- Buckaroo Banzai: Oh.”
Kent Perkins - Mission Control
Peter Weller - Buckaroo Banzai

“- Hillary Flammond: My uncle was born in America.
- Nick Rivers: Oh, really?
- Hillary Flammond: But he was one of the lucky ones. He managed to escape in a balloon during the Jimmy Carter presidency.”
Lucy Gutteridge - Hillary Flammond
Val Kilmer - Nick Rivers