Articles related to the character Uncle Sam and his depictions. He is a common national personification of the federal government of the United States or the country in general. Since the early 19th century, Uncle Sam has been a popular symbol of the U.S. government in American culture and a manifestation of patriotic emotion. Uncle Sam has also developed notoriety for his appearance in military propaganda, popularized by a 1917 World War I recruiting poster by J. M. Flagg.