I'm here referring to the famous "Northern Cities Vowel Shift", which I first noticed in the late 1960's among people just months younger than myself, in the form of "aesc raising", which means that the vowel "aesc" (pronounced "ash") is raised so that it's pronounced "ay", so that "bag" is pronounced "bayg" (rhymes with "Haig").This sound change irritated me like you wouldn't believe, but has since morphed into a proper vowel shift, such that, in my native Milwaukee, if you ride the bus to your job, you say that you "ride the boss to your jab"! Anyways, I've very tentatively traced the origin of this vowel shift back to Southern Appalachia, very likely via US Highway 23, the legendary "Hillbilly Highway". This makes sense, as the aesc-raising which began the whole vowel shift would have taken root in Chicago and Detroit during the Second World War or so, and have spread from there at least as far as Winnipeg, Manitoba, Canada, as exemplified by the speech of television news correspondent Ashliegh Banfield, whose speech displays aesc-raising, yet not the rest of the vowel shift. Yet this is nothing new, as the global spread of the English language clearly marks her as a proto-language, due for breakup into daughter languages. This was evident as early as the Second World War, when the US and Canadian soldiers famously got along with their British counterparts, save in armored and mechanized units, where brawls frequently broke out due to the differences between North American and British automotive vocabulary.