Forum:104 days of summer vacation?

I'm trying to figure out the days count for the american summer vacation.

As you may have already guessed I'm not an american, and I've been looking for references to support the series theme song statement of 104 days, but couldn't find any (including Wikipwdia). All I have found is about 90 days.

Could anyone please lay out the numbers and dates of this vacation in the american education system for me?

Thanks

Oren