If I could hazard a guess, I think the popularity of abolishing the summer break started around the time when the sunbelt started to see a huge migration influx

If I could hazard a guess, I think the popularity of abolishing the summer break started around the time when the sunbelt started to see a huge migration influx. Energy costs skyrocket for large buildings (like public schools) during the summer months, plus outdoor sports are untenable because of the extreme heat, so it would be a huge obstacle for many organized sports. Just a guess. I agree otherwise. Public schools could have a more rigorous curriculum while being much more relaxed if the semesters weren't condensed into 4-5 months.