Why is Labor Day in September, and why is it such a big deal?

Just as Memorial Day has come to be thought of as the "beginning" of summer, Labor Day generally is considered its official unofficial end. But just try telling that to Georgia's kids, who've already been back in school for weeks.

So why is Labor Day always in September?  And why does this somewhat taken-for-granted holiday matter so much for America?

(Hint: It has nothing to do with car or mattress sales).

Here are the seven things you really need to know about Labor Day:

 It all began with one "monster labor festival." That might sound more like a description of the goings-on at Bonnaroo or Dragon Con. But in truth, Labor Day's beginnings go back about a century and are rooted in a serious workers' rights movement. Rallies and other events aimed at bettering labor conditions were becoming increasingly frequent in the late 19th century, when work days were long (10 to 12 hours), "living" wages weren't for many, and the United States had the highest job-related fatality rate of any industrialized nation in the world.

But the event that’s generally considered the tipping point happened on Sept. 5, 1882. That’s when New York’s Central Labor Union organized tens of thousands of workers to come together for a self-described “monster labor festival” that began with a parade and proceeded on to a park for a picnic, speeches and -- hey, this is America! -- fireworks.

   Like Labor Day? Maybe you have a tuba player from New Jersey to thank. The success of that first event was hardly assured. Police, expecting a riot, showed up in force on the morning of the parade; meanwhile, no one knew how many workers -- most of whom would have to forfeit a day's pay to be there -- would show up to march. Those who did reportedly remained rooted in place at first because there was no music for them to march to. While some urged cancelling the whole thing,  organizers suddenly received word that "two hundred marchers from the Jewelers Union of Newark Two had just crossed (over on) the ferry," an official history recounts on the U.S. Department of Labor's web site. "And they had a band!" Some 10,000 to 20,000 people wound up marching that year, the DOL says.

But let's not overlook the right honorable gentleman from ...  South Dakota? Buoyed by that initial success, the CLU repeated the event on Sept. 5, 1883. Soon, individual states started creating so-called "labor days" -- in 1887, Oregon, New York, New Jersey, Massachusetts and Colorado all made it an official state holiday. More states followed suit, and on June 28, 1894, Congress enacted a bill making it a federal holiday. "Being and celebrated the day known as Labor's Holiday," the legislation that had been introduced the previous year by Sen. James Henderson Kyle of South Dakota grandly proclaimed, "is hereby made a legal public holiday."

 Take a hint, Fourth of July! The first so-called Labor Day, on Sept. 5, 1882, took place on a Tuesday (the following year, it fell on a Wednesday). Luckily for fans of three-day weekends, the legislation that made Labor Day a federal holiday also established it henceforth and forevermore as being celebrated on "the first Monday of September in each year." The earliest date Labor Day can take place in any year is Sept. 1 (most recently in 2014) and the latest date is Sept. 7 (most recently in 2015).

Related video: How to spend your Labor Day weekend in Atlanta

Without Labor Day, Summer would just go on and on and . . . Sounds pretty nifty, right? But without Fall, there'd be no Halloween, no college football playoffs and -- gasp! -- no Pumpkin Spice Lattes! Summer may officially end on Sept. 22, but like we said before, most people consider Labor Day to be its end point. But here's where it gets really interesting. Memorial Day, aka the "first day of summer," always takes place on the last Monday in May. The earliest date that can be is May 25 -- and that always occurs in the same years in which Labor Day arrives latest, on Sept. 7. In other words, summer is much "longer" in those years (a full five days longer than this year, just as a f'rinstance). The next time it will happen is in 2020.

Meanwhile, kids in Virginia would just be riding roller coasters forever.  A 1986 state law there says public schools can't start before Labor Day without a waiver from the Virginia Department of Education."Supporters of the current law say that it helps protect Virginia's tourism industry," the Virginia Gazette wrote earlier this year about an unsuccessful legislative attempt  to end what's been nicknamed the "Kings Dominion Law." Because the holiday period can represent a last chance for family visits, the article explained, "Theme parks like Kings Dominion and Busch Gardens have advocated keeping schools from starting before Labor Day." But before Georgia students get any ideas, it seems waivers are increasingly winning out: A Richmond TV station reported on Wednesday that an estimated 65 percent of the state's public school students had returned to class before Labor Day this year.

Finally, go Falcons! After Labor Day, along with the rest of the NFL. Even the mighty NFL takes a cue from Labor Day. On Sept. 5, 2002, the NFL opened its season for the first time ever on a Thursday night with a game between the New York Giants and the San Francisco 49ers at Giants Stadium. Coming three days after Labor Day and just before the one-year anniversary of the Sept. 11 attacks, the game was preceded by "NFL Kickoff Live" from Times Square, "a football and music festival honoring the resilient spirit of New York and America." Every year since then, the high-profile game has kicked off the NFL season on the Thursday after Labor Day (the lone exception: in 2012, it was played on the Wednesday after the holiday to avoid conflicting with the Democratic National Convention). Since 2004, the defending Super Bowl champion has played in the NFL Kickoff game. Sigh. Next year, Falcons fans. Next year.