Treatment of indigenous peoples around the world is also another big blinders, although the US has done one of the better jobs of being forthright about poor treatment (compared to Canada, say).

A summary of the book is that history textbooks have a tendency to avoid showing anything negative done by great American historical figures because they are held up as heroes for people in imitate. There is a narrative of constant progress that is told in the textbooks that does not match with actual history. History textbooks avoid talking about class struggles altogether, because if they did they would be labeled as Marxist. There is a general avoidance of discussing immoral foreign policy. The book backs up these claims by citing many popular textbooks and how they cover, or don't cover, historical events.

(The following summary of the book is my own understanding of the book's opinions and not necessarily my own. I haven't studied history enough to hold my own opinion.)