In reply to:
U.S. vs British English
I read an excellent explanation in a scholarly book about a year ago, but I gave the book away and don't remember the title or author. This author's explanation is:
Originally, there were two American dialects of English, the New England and the Virginia. From researching the origins of the early emigrants, it appears that the vast majority of the first settlers in New England were from eastern England, East Anglia and Norfolk, and they spoke English with the flat vowels and elided 'R'. The vast majority of the first settlers in Virginia were from southern England, mostly from Kent, and spoke with the deeper rounder vowels and the soft 'R' (this is the American dialect most like modern British). Later on, those who came and settled western NY, Pennsylvania, Kentucky and Tennesee were mostly Scotch-Irish from Ulster, speaking with the hard vowels and hard 'R' of that area. This has, over 200+ years, morphed into the standard U.S. dialect. This is the gist of a complicated explanation backed up with reams of demographic data.
Meanwhile, there is the fact that beginning around the 1720's in London, a shift in pronunciation began. Up to then, British and American usages and pronunciation were pretty much the same, depending on where you were from. But a new pronunciation with different vowel values and stressed syllables etc., got under way, which culminated in what is now the (more-or-less) standard British usage. The colonists, however, being to a fair degree isolated on this side of the Atlantic, did not participate in this neology, but stayed with the old usages they had brought with them. (In the same way the Canadians held fast to the French they came with, in the face of changes in the language in the motherland.) Thus it may fairly be said that American English is more like the English of Cranmer, Shakespeare, Donne, Milton & Dr. Johnson than modern British English, just as Canadian French is more like the French of Moliere and Racine than modern continental French.