The best examples of the “upper crust” accent I can think of are Eleanor and FDR, and Margaret Dumont (the quintessential society matron in several Marx brothers’ movies).
What is the origin of that accent? East Coast? New England? New York?
When elocution was taught, was this the way people were taught to speak?
I think it is mainly from Eastern Massachusetts including Boston, Cape Cod, Martha’s Vineyard, and Nantucket. There aren’t many people that speak like that anymore. The only ones I have ever heard have been in their mid-fifties at best. I have never heard a younger person speak that way.
One a similar note, while we’re at it, whence the aristocratic accent in England? I’ve noticed all the Bristish Army officers have a similar accent, though they range from all over England.
The stereotypical old-fashioned American upper-crust accents go by several names (perhaps with some differences): “Locust Valley lockjaw” for New York examples (like those of the OP), “Boston Brahmin accent” for New England examples (as several of you mentioned), “Main Line accent” for Philadelphia, and least colorfully and most confusingly, “Mid-Atlantic accent” (which is a hotbed of ambiguity, meaning several other things as well).
Incidentally, I don’t think this cluster of accents is really all that narrow; that is, even if it may seem otherwise, I think there are wide variations within the spectrum of “that upper-crust American accent”, even on such major axes as whether to pronounce post-vocalic /r/s or not.
I suspect it comes from where they go to school - officers are perhaps more likely to be from an higher class background, go to the same or similar posh schools regardless of the actual *location *of their birth, then go on to officers training college. I can’t remember where the college is, but I think Prince Harry went there.
When I lived in Kansas City several years ago, one of the female announcers on the local NPR station (KCUR) spoke in an old-school Connecticut Lockjaw. KC seemed like the last place where one would expect to hear the old Northeastern upper crust “oh, pshaw!” accent.
I also mourn the decline of the Cheektowaga accent (“dat der Chickatavaga aksint dere”, known by linguists as the Polish ethnolect variant of the Buffalo accent; Cheektowaga’s residents now tend to speak in the standard Buffalo “eyacksint”, with a shrinking number of older residents speaking Chicktovegan) and, for lack of a better term, the “old black man accent”. Yiddish inflections also seemed more common in the past among American-born Jews than now.