How the USA transmits its colds to the world

 The saying goes: if the US sneezes, the rest of the world catches a cold.  

There are good reasons for this:  the USA is the world's largest economy; it sets its monetary policy independently, whereas most other economies have to at least consider US policy; it has the world's largest capital markets; it owns the world's reserve currency.  So what happens in the US affects sentiment in other stock and bond markets and sentiment and policy in other economies.

But there is also a strong direct link.  As in most economies, the volume of imports is strongly correlated with domestic economic activity.  As its economy slows, the US reduces its imports.  And that leads to exports falling in other economies, which in time leads to their economies slowing too, even without them following the US in raising rates.

Both series extreme-adjusted.
See how import volumes slightly lag at the bottom of the cycle.