I never even heard of Spring Break, until I was an adult. We didn't have it in school, and when I did hear of it, it had something to do with universities.
Now, all schools seem to take a Spring Break. I'm guessing it's a subtle long term effort to come up with another national holiday, which allows another reason to not work, and retail outlets to peddle their wares with false guarantees of the lowest prices all year.
Time will tell.