I think the biggest one would be inadequately portraying America as always being the 'good guys'. Specifically not really ever mentioning our role in undermining democracies in third world countries all over the world.
I think there should be more focus on economic history at least in university level courses. While some of it is horrifically boring, it can be very interesting, at least in my admittedly biased opinion.
Are we talking at the high school level or the college level. As a college instructor, I find myself having to correct numerous inaccuracies. For example, /u/why_the_love's post, at my university, the American history curriculum is an active rebuttal of many of the tropes of American History as taught in high school.
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