How did the development regional economies and the growth of nationalism complement and contradict each other?

The development of regional economies helped to complement
the growth of nationalism in a way because the regional economies, though separate, were
connected.  For example, the regional economy of what is now the Midwest was connected
by water to the Northeast.  Similarly, the Southern economy depended on the North for
things like shipping and insurance and some manufactured
goods.

Of course, these developments also contradicted each
other.  The development of regional economies made the regions less similar to one
another and less inclined to get along.  This contradicted the growing tendency towards
more of a national feeling.