Books
In this country American means white. Everybody else has to hyphenate.
— Toni Morrison · The Guardian (29 January 1992)
Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Morrison points out that, in this country, 'American' quietly defaults to white, so everyone else needs a modifier attached. The hyphen becomes a symbol of being treated as partly outside the label. It's a comment on who gets to be assumed, and who has to qualify.
Context reviewed