If you're important or whatever you're doing is important, it's marked with an American flag. All kind of things are printed with the flag on it: towels, bikinis, lighters, ...
Today I was impressed by this installation:
There's a flag at the tip of the tower crane on campus! There must have been somebody who has brought it there (it might have been pre-set, but I doubt that).
Thinking of my travel to New York and its Museum of Modern Art, I remember a painting of the American flag:
http://www.moma.org/collection/works/78805
It's not simply a painting and the Museum was not sure if they could accept it as "art", but after it passed several hands somebody finally gave it to the museum as a donation and they couldn't refuse it. However, there are only 48 stars in this flag and they are not diagonal, so we can assume it's art ;)