I suppose it depends on how you define the beast of Rev 13. The americas could certainly be a part of it, but I don't see anything which demands that they are (or demands that they aren't for that matter).
From what I read in scripture it would appear that the beast of Rev 13 (and the same again in Rev 17) represents both a Man, and a system, or a kingdom.
From one standpoint, the beast is the kingdom of this world. In scripture there are two kingdoms, two cities, two households, whatever you prefer to call them. They begin at the very beginning with Cain and Abel (and seth as abel's replacement) and they go all the way down through the bible from that point on. Cain's legacy is the kingdom of this world. Cain founds the first city, his descendants make most of the advancements considered to make up civilization. While Seth's line are mostly nomads and heardsmen (as was Abel).
After the flood the line picks up with Babylon as Cain's legacy, and Abraham as God's remnant. Abraham is called out of babylonia (the city of UR specificly) into a life of wandering, seeking for a promised home.
This trend continues down through the entire bible. The kingdom of this world is at home, it is settled, the remnant of God is not at home, they wander, looking for a promised land.. they are shephards.
The beast is that World Kingdom which has been since the beginning, and it has always been trying to destroy God's remnant.
The seven heads are the seven great embodiements, or achievements of the world kingdom. Four of the heads are revealed to us by daniel, the others are not directly revealed, but aren't hard to guess when you see the pattern.
The four revealed by Daniel were Babylon (nebuchadnezer), Medo-Persia (Cyrus), Grecia (Alexander the Great), and Rome (Nero). Daniel only saw in his dream those that were in the future from his time.. thus he did not see Assyria or Egypt represented because they had already come and gone, but they are most likely included in the beast of revelation.
John says in Rev 17 that 5 of the heads had fallen, and one was in his time.. that is Rome, then the five were Greece, Persia, Babylon, Assyria, and Egypt.
That leaves 1 of the seven, which John says "will remain for a short time".. this one is debatable. I've always tended to favor Nazi Germany, but it could be something else, maybe something yet to come.
The beast also represents a man, who is number 8 on the list above.
When it says that one of the heads was mortally wounded but yet returned, many have thought this meant one of the kingdoms, others think it means one of the rulers.. it could mean both... or possibly neither
We are told in Rev 17 that the beast "was, is not, and will come up out of the abyss". This tells us that he is currently in the abyss. That raises the question is the abyss the same place as hades? Hades is where the souls of the dead humans went.. but the abyss seems only to be mentioned in the case of evil spirits. So this could strongly suggest that the beast is actually an evil spirit.. a principality which drove one of the ancient kings. (similar to how John the Baptist came in the spirit and power of elijah).
We know from daniel that there were demonic principalities which ruled over the ancient realms, perhaps the beast is one of these. Perhaps he also was the driving spirit behind someone like Alexander the Great.
We have limited detail to work with in such deductions so in the end its mostly guess work.
But, the beast represents not just a kingdom, and not just a man.. but both, and an over-arching system.. the city of Man as Augustine called it, the Kingdom of this world.