[scalziand]

Engineers have been working on designs for 100-200 floor skyscrapers since at least the early 80's. However, they tend to be pretty uneconomic. Currently, the economics tend to fall off above ~80 floors. This is why the tallest towers proposed/u/c in NY and Toronto fall in this range(even 1WTC). Internationally, when a developer wants a landmark tower, and they want to stretch above that limit, they might as well stretch just enough to get the magic 100 number, or in Asia, to 108, 118(Hong Kong ICC), or 128(Shanghai Tower) floors, because 8 is considered a lucky number. This also explains why there are relatively few 90 floor towers.