The Lost Tribe of Manasseh is the modern United States.
Jacob's prophecy about Manasseh:
17And when Joseph saw that his father laid his right hand on the head of Ephraim, it displeased him; and he held up his father's hand, to remove it from Ephraim's head to Manasseh's head.
18And Joseph said to his father, Not so, my father; for this is the firstborn; put your right hand on his head.
19But his father refused, and said, I know it, my son, I know it; he also will become a people, and he also will be great: but his younger brother will be greater than he, and his seed will become a multitude of peoples.
20And he blessed them that day saying, By you Israel will bless, and they will say, May god make you as Ephraim and as Manasseh; and thus he set Ephraim before Manasseh.
The blessing given to Ephriam and Manasseh upset their father Joseph because Jacob apeared to be changing the natural birthright promises.
The passage suggests that Manasseh would inherit Abraham's Great Nation promise while Ephraim would become a community of nations.