To begin with, White reminds us, the original Americans always pronounced r, as the British did in colonial times. Only in the late 18th century did the British stop pronouncing r after a vowel. Not surprisingly, the colonists who remained in the big East Coast seaports and had regular contact with London adopted the new British pronunciation. But those who settled inland retained the old r and never lost it. (As White says, this means that Shakespeare’s accent was probably more like standard American today than Received Pronunciation.)

— Tawk of the Town, Patricia T O’ Conner in Literary Review