Samuel Wilson, meet Isaac Mayo. Now, will the real Uncle Sam please stand up?

A history professor in Nebraska tracing the origin of the popular personification of the United States government has fleshed out a reference to Uncle Sam that predates the traditional wisdom that the nickname was derived from Wilson, an upstate New York butcher who would stamp the meat he delivered to the military with the initials “U.S.” during the War of 1812.

That notion was popularized in 1830, in The New York Gazette and Daily Advertiser. Wilson’s claim to the name was recently buttressed by Christopher K. Philippo, who is researching a book on cemeteries in Troy, N.Y.; he discovered a letter from the Rev. Robert Russell Booth, who presided over Wilson’s funeral, and wrote that he “often talked with him about the circumstances which led to the singular transfer of his popular name to the United States.”

But other historians suggest that Uncle Sam predated Samuel Wilson. Barry Popik, an etymologist, has pointed out that in 1813 the upstate Troy Post, without mentioning Wilson, explained the derivation this way: “The letters U.S. on the government waggons, &c., are supposed to have given rise to it.”