It largely boils down to the fact that the US is the worlds highest consuming country. Oh boy, do they know how to spend!
To give one example just so you get the idea. When US unemployment increases there are fewer people with money to spend so fewer cars,houses (you name it) are built so there is less demand for say steel hence there is less demand for our coal and iron ore etc. I suppose it could be called a domino effect.
The present connection between the US and Australian markets will diminish over time as Chinese and Indian domestic spending grows.
