It's in the Bible in a round about sort of way: In effect (I don't remember the exact quote or book) saying that those who bless Israel will be blessed --- and we helped create and defend the modern state of Israel ---- while those that CURSE Israel will themselves be cursed. Unfortunately, recently we have been distancing ourselves from Israel. The Presbyterian Church (USA: The Liberals) has just officially disinvested itself from Israel and is pushing others to follow suit. If this trend continues, we may find ourselves on the "outs" with the Lord as a nation, not as individual believers.
Also, the Bible make no specific reference to the USA in the Book of Daniel or Revelations. I personally believe that for the Kingdom of God to be realized, for the Rapture to occur and the true AntiChrist to arise (no matter if you disagree with that or not) this country must be toppled from the world stage in a major way. Even driven to it's knees.
Have you ever read George Washington's vision?