All across the United States, people are weeping. They are sobbing, sputtering, sniveling and mewling because they are in the process of saying goodbye to their little baby boy or little baby girl who somehow has passed through the larval stage to emerge suddenly as this new creature called a college freshman.

The parents have been dreading the Great Goodbye for years. They are in the throes of a massive attack of Separation Anxiety. Dad tries to be stoic, but suddenly has a cantaloupe in his throat. He swings his arms and tries to find some use for his hands. For some reason, millions of years of evolution have not given him the psychological adaptations necessary to drop a kid at college. Mom – who has rehearsed the moment many times, only to find herself rushing through it and missing key lines – issues last-minute recommendations and requests, most of them implausible notions about hygiene, studiousness and calling home daily. The college freshman, half-listening, is thinking about the rumored rager that’s going to bust out later on the roof of the dorm.

I write from some experience, having gone through the drop-off ritual three times. At times you sense almost a competition among various parents to proclaim the greater emotional trauma.

“We cried for 300 miles on the drive back home,” one parent will announce.

Another parent will say, “In the living room we built a small shrine to Junior, with an Eternal Flame, and every night we set a place for him at the dinner table in case he comes in through the door miraculously.”

And a third parent will say, “We kicked our kid out of the van, said ‘See ya!’ and went straight home, where we engaged in nonstop sex for four days in the living room, dining room, kitchen and on the backyard trampoline.”

My point being, your mucilage may vary.

After I dropped my eldest child at college in 2009, I wrote an essay about life’s milestones, and it got pretty teary and sniffly and blubbery toward the end, as I tried to explain the special pain of the college drop-off:

“A child’s milestones are the parents’ milestones, like that first day of preschool, with its excruciating goodbye as the child is abandoned to what, from the child’s perspective, is surely a devil-worshipping cult. There’s the first lost tooth, first soccer goal, first-time rolling of the eyes and dramatic sigh at exasperating parental behavior. The first slammed door. The first time Dad accidentally embarrasses her in front of her friends; the first time Dad intentionally embarrasses her in front of her friends.

“After all these milestones, why does dropping the kid at college turn into such a weep-fest?

“My theory is that it’s because you sense, even if you can’t think it through logically, that you now have finished the task of raising a person to adulthood, and, with the exception of raising your other children, there is nothing else you will ever do that’s as important. This is the largest achievement of your life. Everything else is secondary, tertiary, quaternary. Basically the main job of your life is pretty much over.

“The very term “milestone” is deceptive, for on a road you can always turn around and retrace your steps. Life’s milestones are actually one-way portals. They’re gateways to whatever is next, and they close behind with a resounding clang.

“What you want is to be able to say: We had us a good trip, didn’t we?”

Yeah, that was a weepfest for the ages, that drop-off.

The cruelest quality of time is that it flows only in one direction. The arrow of time. There are no do-overs. What’s done is done.

But here’s the good news: Parenting doesn’t end when they go to college.

Back in 2009, when we were about to drop the eldest kid at college, and were mushy and inconsolable about the whole thing, our older, wiser friends had a message for us: “They come back.”

Remember those three words. It’s true. They come back, they cycle through, they pop in and out. They often bring the whole train of friends. Sometimes they stay for a couple of months or longer. There’s an understanding these days: Coming back home is an option. And we’re way beyond the Failure to Launch trope. Boomeranging is the new normal.

There’s also this new thing you discover one day that I guess is called Distance Parenting. Kids need advice and support. Who’re they gonna call? The people who know them best and care about them the most. People who have only their best interests at heart. The original investors in the enterprise that is their life.

The rhythm of the relationship has obviously changed at this point. As a parent, you’re no longer the supervisor. You’re the counselor. And the No. 1 fan. You’re the one who will always take a call at any time of day or night.

Operators are standing by.