So you can be sure I'm not just talking out of my ass, "A Short History of United States Education, 1900 to 2006". TL;DR: Between 1900-1919, enrollment in kindergarten was 7%. Only half of the school aged population was enrolled in school. Half of the student population didn't achieve graduation from 8th grade. In 1910, only 37% of 17 yr.-olds were enrolled in high school. 8% of students graduated from high school.
Tell me again how much better education was in the past?
I think it could be that you're doing more than a bit of apples to oranges there. For instance, kindergarten is a fairly recent concept: is there actual evidence that it improves education outcomes, or does it just act as a babysitter for working parents? (Same could be said of Head Start programs, the evidence for which seems, at least to a casual observer like me, decidedly mixed.)
Likewise, when comparing high school graduation rates, we need to adjust by what the graduates actually know. I'm sure we've all seen the (possibly apocryphal) high school exams from the 1800s that most college grads today would fail.
Sorry, I realized after I posted and walked away that I didn't make myself clear. I did sorta mean that it was an apples and oranges comparison, but also that a romantic, rosy view of the past is ludicrous. We can't compare schools now with schooling then because only the privileged children went to school, and most of them knew that it was a privilege to do so.
Also, if you know you've got to cram as much knowledge into a kid's head as possible because they're not going to go past 8th grade, wouldn't you try your best? However, the numbers show that most kids didn't even graduate from that grade, so how do we know they actually passed those tests?
Finally, they might have known more in those categories at the time, but think of how much human knowledge has expanded since then. Think of science, especially biology but also chemistry and physics! Holy crap, we've got so much more to learn now. It's a beautiful, glorious thing, but again trying to compare to the past is apples and oranges.
As for kindergarten, the article I linked to (did you read it?) says that at the time, it was a 30-year-old concept. I was just grabbing a lot of the pertinent facts from the article, which is why I included the kindergarten concept. I also think kindergarten is (or should be) more about learning group dynamics than it is about learning any testable skills. Just MO however.