Uncle Sam, name used to designate the U.S. government. The term arose in the War of 1812 and seems at first to have been used derisively by those opposed to the war. Possibly it was an expansion of the letters "U.S." on uniforms and government property, but some sources attribute the origin of the term to Samuel Wilson (1766–1854) of Troy, N.Y. Wilson, whose nickname was Uncle Sam, was an inspector of army supplies. The "U.S." stamped on supplies was referred to as "Uncle Sam" by the workmen. Regardless of origin, the term found wide application and became permanent.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
More on Uncle Sam from Infoplease:
See more Encyclopedia articles on: U.S. Government