Since the early 1970s, the federal government has tracked the academic achievement of American 17-year-olds.

The results have been essentially flat despite the fact that per-pupil has more than doubled, even after adjusting for inflation.

Presented with this dismal national picture, many pundits and elected officials protest that their own states have done better.

The trouble is, there’s been no way to verify their claims. State-level test score averages don’t reach back that far, or, as with the SAT, they aren’t taken by a representative sample of all students.

But there’s a way over this hurdle: State-level academic trends can be estimated all the way back to 1972, and the results aren’t pretty.