How did "Uncle Sam" become a symbol of the U.S.?

Answer 1

A ridiculously easy wikipedia reference would give you all the information you need

http://en.wikipedia.org/wiki/Uncle_Sam

Answer 2

Uncle Sam is a national personification of the United States, with the first usage of the term dating from the War of 1812 and the first illustration dating from 1852. He is often depicted as a serious elderly man with white hair and a goatee, dressed in clothing that recalls the design elements of the flag of the United States—for example, a top hat with red and white stripes and white stars on a blue band, and red and white trousers.

Origin of the Name
Common folklore holds origins trace back to soldiers stationed in upstate New York, who would receive barrels of meat stamped with the initials U.S. The soldiers jokingly referred to it as the initials of the troops' meat supplier, Samuel Wilson of Troy, New York. The 87th United States Congress adopted the following resolution on September 15, 1961: "Resolved by the Senate and the House of Representatives that the Congress salutes Uncle Sam Wilson of Troy, New York, as the progenitor of America's National symbol of Uncle Sam." A monument marks his birthplace in Arlington, Massachusetts, and a monument marks his burial in Oakwood Cemetery, Troy, New York. The first use of the term in literature is seen in an 1816 allegorical book, The Adventures of Uncle Sam in Search After His Lost Honor by Frederick Augustus Fidfaddy, Esq., also in reference to the aforementioned Samuel Wilson.

Another theory suggests that Uncle Sam was a creation by Irish immigrants to the U.S. who used the Gaelic acronym, SAM, or Stáit Aontaithe Mheiriceá, which is the translation for United States of America, as a nickname for their new host country. However, the precise origin of the term may never be proven.

Earlier representative figures of the United States included such beings as "Brother Jonathan," used by Punch magazine. These were overtaken by Uncle Sam somewhere around the time of the Civil War. The female personification "Columbia" has seldom been seen since the 1920s.

THERE IS MORE INFORMATION AT ''Wikipedia''.

Answer 3

uncle sam is a imitation of british lord kitchner who was used a sa recruiting method during ww1 with the infamous words uncle kitchner wants YOU. Uncle sam was just a adoption of him.

Answer 4

to much to list here. try wikipedia. they have an article on it.