 Since the early 19th century, Uncle Sam has been a popular symbol of the US government in American culture and a manifestation of patriotic emotion.While the figure of Uncle Sam represents specifically the government, Columbia represents the United States as a nation.The first reference to Uncle Sam in formal literature (as distinct from newspapers) was in the 1816 allegorical book "The Adventures of Uncle Sam, in Search After His Lost Honor" by Frederick Augustus Fidfaddy, Esq.