This is a wonderful survey titled Legislative Control of Elementary Curriculum. It was authored by Jesse Knowlton Flanders in 1925.

His research question is simple: What are the 48 states (yes, 48) requiring students to study?

Flanders utilized statutes from each state to derive his findings.  Not surprisingly, in a time when the federal government had very little involvement in the schools, each state has its own idiosyncratic curriculum.