So how did the accent die? Thanks in part to these sharp-tongued headliners like Bogart, Americans began to see themselves better reflected in film. The Mid-Atlantic accent was very much in vogue until its abrupt decline post-World War II. Taught in finishing schools and society parlors, the accent had become common to off-screen America. But more people spoke as they do today, with regionally developed accents like Boston Brahmin or Locust Valley Lockjaw. The rejection of Mid-Atlantic was also a rejection of classicism. Highfalutin figures in American society who luxuriated in the vernacular were edged out by the everyman. "This idealization of the linguistic behavior of upper class Americans continued, in some Hollywood films, up to the late '40s and '50s," says Dr. Marko Modiano, senior lecturer in English studies at Gävle University. "It lost its position with the rise of a new generation of film stars who, like everyone else, were moving more and more toward the kind of neutral American English which we hear today in the US."

Rita Moreno, who started off on stage in Singin' In the Rain and later on screen in West Side Story (1961), told NPR, "I became the house ethnic. That meant that I had to play anything that was not American. So I became this gypsy girl, or I was a Polynesian girl, or an Egyptian girl. Finally, I decided by playing all these roles, I should have some kind of accent. But of course, I had no idea what these people sounded like, so I made up my own." What Moreno didn't realize is that her "ethnic" accent already existed, or at least, what she used as a foundation did. It was Mid-Atlantic English with ethnic injections and clipped delivery.

Nowadays, ethnic injections are only the result of behind-the-scenes training. Social media's ability to mass-ridicule a crummy rendition of a foreign accent means that speech coaches are written into contracts. Barbara Berkery helped concoct Johnny Depp's inebriated mumble for the Pirates of the Caribbean franchise, which has ruefully seeped into Depp's subsequent roles (The Rum Diary, The Lone Ranger). And just to confuse things, Brits have spurned typecasting for the role of butler and are increasingly putting on American accents to win over US markets. Henry Cavill, the Channel Islands chap who plays Superman in this summer's Man of Steel, did some heavy lifting to affect a Midwest manner of speech. "Doing an accent is like going into the gym for a workout," he tells Collider. "If you pick up the heaviest weight possible and try and clean and press it, you're going to pull something." For Emma Watson's Calabasas caw in The Bling Ring, she marathoned through several seasons of Keeping Up With the Kardashians to match the sisters' vocal fry.

Marathon as they might, though, few of today's actors will ever need to perfect a widely heard but invented dialect. Mid-Atlantic English defined an era on screen by lending films an escapist, more-refined-than-reality allure. As Hollywood's golden age was ushered out, the accent went with it. Katharine Hepburn and Jimmy Stewart's romantic spat in The Philadelphia Story offered a metaphorical damnation of the high-society cinema accent. "Shut up. Shut up. Oh, Mike, keep talking. Keep talking. Talk, will you?" Hepburn pleads. To which Jimmy Stewart's character soberly states, "No, no, I've... I've stopped." And so, too, did Mid-Atlantic English.

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