akuperma,
” In America there are regional accidents, though mid-western (mid-Amerca) became standard as a result of the civil war (when someone from Illinois accepted the surrender from a Virginian)”
I don’t think this is quite accurate. Lincoln himself spoke with a distinctive Kentucky twang. I think the “American Standard” dialect developed conceptually more in the 20th century with suburbanization (middle class whites eschewing regional accents perceived to be associated with poor inner city areas, and favoring accents more similar to Anglo-Saxon residents of the interior Northeast and Midwest), and television and radio broadcasts that adopted the same. A possible Civil War connection may be the association of Southern accents with stereotypes of poverty and slowness, due to the extensive poverty in the South following the war. Regional accents in the Northeast were likely associated with poverty due to the high number of new immigrants in the early 20th Century.