True story: my wife majored in Musical Theatre in college, and had the privilege of studying with Rocco Dal Vera (http://www.ccm.uc.edu/faculty/facultyProfile.aspx?facultyid=32/), a world-renowned dialect expert.
To put in context how freaking awesome this guy is: name a country in the world, and he can perform every dialect in the region flawlessly, as well as tell you how it originated and developed over time.
Awesomeness indicator #2: Rocco did the dialect work on the "Indiana Jones" movies. 'Nuff said.
Yesterday, my wife e-mailed the "Did Americans in 1776 have British Accents" post (http://www.nicholasjohnpatrick.com/post/767354896/did-americans-in-1776-have-british-accents) to Rocco. Here's his reply, posted here with his permission:
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That is very cool, and I found most of the post accurate, except at the end when he speculates on why New York and New England may be non-rhotic.
There's a small contradiction: if their connections were British and British was itself rhotic, then that doesn’t explain how they lost their Rs. (Except that it could have happened 100 years after the Revolutionary War.)
England’s journey toward a non-rhotic prestige accent followed the Revolutionary War, a time when we were pretty cut off from them. We were in a state of almost continual war with them through the war of 1812 and even through the Civil War when they supported the South more than the North.
Much later, in Victorian times, wealthy residents of Boston, Philadelphia and New York sent their children to England to be educated and their prestige accents became reflective of those schools’ emphasis on RP. That persisted well through the 1950s (and shows up in accents we call Boston Brahmin, Philadelphia Mainline and New York 400). It may well be that until then New York wasn’t terribly non-rhotic, but I would love to read a real study on this.
Immigration also had a huge effect on New York and New England speech. How much that accounts for the rhoticity question is hard to say. But is has to be a factor. Still, the result is surprising because notice how Boston, famously the center of Irish immigration (a heavily rhotic accent, then and today) somehow ended up with a non-rhotic accent in a country that is mostly rhotic.
Incidentally, the author doesn’t comment on US Southern prestige accents that were non-rhotic almost from the start. The reason for that? They were raised by their black nannies and African languages are non-rhotic. Southerners hate to hear this, but their prestige non-rhotic plantation accents are the product of slave speech! A lovely topic for the 4th of July as we contemplate liberty...