Statistics for occurrence #1 of “Missouri” in chapter 2.18 of Cambridge History of American Literature: volume 2:
...is due partly to the lack of dialectal distinction in the speech of New York and partly to the more migratory habits of New Englanders and Southerners.
If in the Mississippi Valley and in the Trans- Missouri country a normal American speech free of local idiosyncrasies will first appear, as seems not unlikely, a compromise English dialect will have won its second and greatest victory.
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