How do the u. s. and global economies influence eachother?

Any changes in the global economy affect us, and we affect the global  In other words, instead of having separate economies for each country

Well the U.S. is THEE superpower of the world and greatly influences it, but that in no way means the U.S. dosnt need the world and can be by its self. It stills needs things that it dosnt have or can get in a greater abundance.
Would you need more? or looking for something else?