823! I was born in 1958, which had the highest birth rate of the "Baby Boom" years. Our HS was totally over crowded and they did everything they could to keep as many of us off campus as much as possible...all Freshmen had 1st hour off; all Juniors and Seniors had 7th hour off, and Seniors also had 6th hour off. There were no study halls because there was no place to put them. Best of all (for us) the campus was totally open - we could all leave for lunch - no way they could have fed us all if we had all wanted to eat lunch at school.
My DH grew up in another part of the state but they had it even worse, overcrowding-wise. The students were on "split shifts" meaning some kids went to school at an un-Godly early hour and left early, and then the next shift of kids arrived to go to school into the early evening.