The United States of America is never explicitly mentioned in the Bible. In regard to the end times, the only nation the Bible seems to be concerned with, specifically, is Israel. Revelation does not mention any countries or nations, other than Israel (Revelation 7:4; 21:12). It mentions Babylon (Revelation 14:8; 16:19; 17:5; 18:2,10,21), but beyond that, it does not name specific places. Bible scholars debate whether this refers to a literal city of Babylon or whether Babylon is being used symbolically. Again, Israel is the focus of end-times Bible prophecy.
Why is the United States of America never mentioned in Bible prophecy? This could be for several reasons: (1) Perhaps the United States does not play an important role in the end times. (2) Perhaps the United States does not exist any more once the end times begin. (3) Perhaps the United States is included with all the other nations that reject God in the end times (Revelation 10:11; 11:18; 12:5; 14:8; 15:4; 16:19; 17:15; 18:3,23; 19:15). Option (3) is the most likely answer. The United States of America is the biggest supporter of Israel in the world today. This might not always be the case.