You are right, this is a fairly 'loaded' question.
It could be interpreted in a number of ways, both in terms
constitutes 'American', in addition to the conscious (or
elimination of groups that would end up not being
represented in such
a compendium, who are no less part of the American fabric.
Certainly artists who fit under the title of 'regionalists'
such as Wood
and Benton have been seen as being representative of
types of images, but as we consider what has been
historically, we had better also consider that many cultures
downplayed in those sources, often relegated to a final
chapter at the end of the book.
Also, women artists, until fairly recently in some better
sources, have been so neglected in importance throughout
terms of their contributions, as to be considered a fairly
phenomenon in the art world.
Let's not also forget who the first Americans were either as
this collection of artists.