The etymology of the term "Puke", as describing a resident of Missouri, does not originate from the Civil War, but from either 1830's St. Louis, in reference to cure for nausea ("puke-root") -- Missourians would cross into Illinois looking for the plant, and were referred to as "puke-hunters" or "pukes". Other theories point to the Gold Rush and a corruption of the word "Pike", as in Pike County Missouri (where the famous Sweet Betsy was from).

Any way, the term is no more insulting than "sucker" (Illinois), "Hoosier" (Indiana), Rackensacker (Arkansas) or "Mudsill" (Midwesterner) -- or dare I say it? "Yankee".

Besides, judging historical documents by modern-day standards is a tool of revisionists and the politically correct. I much prefer the term to the nickname "The Show-Me State", which was an insult of Colorado miners against their Missouri counterparts who were not familiar with the peculiarities of placer mining.