A correspondent - presumably from the UK - writes to say she is 'fascinated by the American habit (inability?) to say mirror, terror, etc as we do in two discrete syllables. mir-r, ter-r, is what we hear.' Why do they do it?, she asks. She offers four explanations:
'1. A desire to be stylish or a reluctance to be too correct/too English?
2. Their frequent desire to speed speech up, as in giving a year as Two thousand eight instead of Two thousand and eight?
3. A form of shyness, like saying duiper instead of nappy?
4. Or maybe a Deep South accent becoming unable to embrace it?'
She also asks if we know when such usage began, adding (in a totally different connection): 'the first occurrence I have come across of, for example, would of instead of would have is in Gone with the Wind.'
The answer to the first point is much, much simpler. Most accents of US English are rhotic - that is, they pronounce the /r/ after a vowel. The phonetic character of the /r/ is retroflex, i.e. the tip of the tongue is curled back towards the palate. In words like mirror we find two retroflexed /r/s occurring in quick succession. It is therefore the most natural thing in the world to run the two /r/s together. The alternative, to drop the tip of the tongue for the vowel and then to raise it again, would slow the pronunciation down so artificially that it would sound weird. In fact, nobody ever does this. A 'long /r/' is the result. No need to delve into the imagined American psyche here.
The fallacy in the explanations given by my correspondent is clear when one realizes that this isn't exclusively an American thing. Any rhotic accent will display the same effect. You can hear the same sort of 'long /r/' in West Country UK accents, for instance, or in Northern Ireland, and many other regions. Where did the American /r/ come from in the first place? Think of the people on the Mayflower, and where many of them came from.
As for the spelling would of and other such usages... this isn't a recent American thing either. The earliest instance I have come across of have appearing as of is in one of Keats's letters (5 Sept 1819). And the elliptical pronunciation has probably been around as long as the auxiliary verbs have existed in English. there are several 'ves in Shakespeare, for instance.