what were some of the challenges facing the American people during the late 20th and early 21st centuries

The correct response is "Public education".

Explanation:

American democracy varies depending on knowledgeable and quite well citizens of this country. While less worthwhile a high school degree is, therefore fewer opportunities we have for worthwhile educational opportunities. Almost always, the worse importance placed we position mostly on willingness during the next decade at least to assume for their selves, the further presumably humans are always to risk losing our democratic government as well as the American Way to populist politicians.