The same thing that unites the citizens of any other nation.
Yes, but Brazilian citizens cannot be extradicted to US.
If you mean the Congress of the Unites States of America, then that congress has the power to determine how non US citizens can (if they want) become US citizens. It does not have power to determine the rules for citizenship for any other country.
Till Death Unites Us was created on 2006-01-25.
The answer will depend a lot on who you mean with "us". But in general, getting more united should be both possible and desirable.
US means Unites States as in USA or the United States of America
Unites States of America
Yes, if they are born in the US, they are US citizens.
"History tells us that Europe was antagonistic to the Unites States".
The US flag symbolizes freedom and liberty that US citizens have. The US flag symbolizes freedom and liberty that US citizens have.
The US classifies non-citizens based upon the avenue of entry into the US.
No.
yes