Where did the phrase 'the whole 9 yards' come from and why?
All of it - full measure.
Of all the feedback that The Phrase Finder site gets this is the phrase that is asked about the most often. At the outset it should be said that no one is 100% sure of the origin, although many have a fervent belief that they do. These convictions are unfailingly based on no more evidence than 'someone told me'.
http://www.phrases.org.uk/meanings/the-whole-nine-yards.html< br />
Everything that is relevant; the whole thing. For example, He decided to take everything to college--his books, his stereo, his computer, his skis, the whole nine yards. The source of this expression is not known, but there are several possibilities: the amount of cloth required to make a complete suit of clothes; the fully set sails of a three-masted ship where each mast carries three yards, that is, spars, to support the sails; or the amount of cement (in cubic yards) contained in a cement mixer for a big construction job. [Colloquial] ...more
It draped an Indian woman in all respects and looked gorgeous too around the world.