The 180 day rule (not sure if it was state or federal) was in effect back when I was in school in the '70s. This was in the midwest. We always started after Labor Day and ended around June 20th. We never got a February vacation. Now in that area they start in August, get a week off in February, and end earlier in June. Who knows why.
Where I live in MA, kids usually start after Labor Day and can go until June 30

if there are a lot of snow days. Five are built into the calendar - if they use them all, next year my kids won't be out until June 25.