What was the American colonists' role in British mercantilism?

Under the mercantilist system, the role of a colony was to
help its "mother country."  The mother country wanted to export things that were more
valuable than whatever it had to import.  The American colonies' role in the British
mercantilist system was to help make this happen.  They were supposed to provide
products that could be exported by England and they were supposed to buy valuable things
from England.

This meant a couple of things.  First, it
meant that the colonies would not be allowed to export things directly to other
countries.  Instead, they had to send them to England first so England could benefit
when the goods were exported.  Second, it meant that the colonies were not allowed to
make things that would compete with things made in England.  England wanted the
colonists to import things, not to make their own.

All in
all, then, the colonies' role was to provide things that the British could export and
buy things from Britain.  In both ways, they would help England be able to export more
than it imported.