Sentence:  Nor have we remembered that in the melting pot of <WSD>America</WSD> the hundreds of isolated and semi isolated ethnic , regional and occupational groups did not fuse into a homogeneous national unit until long after education and industrialization had caused them to cast oral tradition aside as a means of carrying culturally significant material . 
Meaning of the word marked with <WSD> tags:  North American republic containing 50 states - 48 conterminous states in North America plus Alaska in northwest North America and the Hawaiian Islands in the Pacific Ocean; achieved independence in 1776