There was already significant federal funding luring students in then, but the big disaster began with the expansion of student loans to everybody for everything in 1991:
https://www.bankrate.com/loans/student-loans/history-of-student-loans/#basic-educational
And our peak year for enrollment was 2010:
https://educationdata.org/college-enrollment-statistics
And you’re so right, only about half of Americans were graduating from high school, at least nearly on time, at least through 1980 (now we’re up to about 80%), so even that level of education wasn’t usually required then:
(Sadly, the typical high school grad was better educated then than the typical college grad is now.)
"... only about half of Americans were graduating from high school, at least nearly on time, at least through 1980 (now we’re up to about 80%), so even that level of education wasn’t usually required then"
Then, I guess, the mantra became "stay in school," so more students stayed in school.
I remember, at that time, high school students were put into 'tracks,' and the schools had many shop classes.
At some point, the schools dropped the 'track' system and the shop classes - or so I heard. Then, I guess everyone ended up on the same 'track,' so to speak?
Then, states started raising their compulsory school age. Now, only 17 states allow a student to drop out at 16. The compulsory age is 17 in eight states, age 18 in 24 states and D.C., and age 19 in Texas.
https://www.ecs.org/50-state-comparison-free-and-compulsory-school-age-requirements/
And now, here we are, thanks to well-meaning intentions.
No one here ever agrees with me on this idea: I think the requirements for a HS diploma might as well be easy/basic, and students should graduate by 15. Then, at 16, they can start college or tech/trade school (or just go to work).
In England, students start either college or vocational school at 16.
Here in the U.S., most states have dual-credit programs for HS students to earn college credit, so those student might as well start college at 16.
The tech school could feature computer certifications, CNC programming, office skills, etc., in addition to HVAC and everything else.