Considering the public education system is kind of a joke, I don't see why they would run that late into the summer.
Granted, my summers as a kid in private school usually didn't end until early to middle June, it seems weird now that school ends in May for most kids now. Keeping kids that late into June should be considered cruel and unusual punishment. Its not like they are learning anything. They are all thinking about going to the beach, the ball games, and the pool. It doesn't make sense to go that late into the year anymore. I rather start in late august and have memorial day weekend as the start to my summer break.
When I was in high school, the last day of school was basically the 17th of May. Exams were the week after. Then the rest was just waiting/graduation practice. Ultimately I graduated June 6th but that was just due to overextending the graduation process.