"Is that the house?"

"No, it's, like, four times the size of that one."

"More like three times."

"It looks like that one, anyway."

"No, it doesn't."

It is the height of summer, and the car, which is full of children, has been humming and intermittently crawling along the New Jersey Turnpike for longer than anyone likes.

For hours, the occupants were sunk in a companionable torpor. Now, however, we are close to our destination. The children have roused themselves; they've suddenly begun to take notice of their surroundings, and -- as invariably happens at the very end of long car rides -- they've commenced to bicker.

"Everyone here is from New Jersey," a child says, looking out the window.

"How do you know?" This said accusingly.

"The license plates all say 'New Jersey.'"

"Yeah, but how do you know the people in the cars are from New Jersey? They could be from anywhere."

"They could be from France or something."

"They're not from France!"

"You don't know that."

If late-journey bickering weren't so annoying, it might almost be endearing. The children are road-weary and have lost all inhibition. They can't seem to help correcting and contradicting each other. Indeed, the urge appears so instinctive that it seems contrived by nature to serve some evolutionary purpose.

Perhaps the purpose is to spur the maddened driver to put on a burst of speed. In this case, it works.

"We're almost at the beach!"

"No, we're not."

"Yes, we are."

A low-flying aircraft crosses the distant sky. It's pulling a long, flickering sign that advertises happy hour at a pirate-themed bar.

"Oh! That is the exact kind of plane that pulls signs along the beach!" a child says excitedly.

"That's why it's up there. Duh."

It's a surprisingly common phenomenon. A Bethesda friend tells me that her six children routinely begin arguing -- after hours of calm -- at virtually the same stretch of road every time she drives them to their grandparents' house, four hours from Interstate 495.

It's got to the point, she says, that she begins to brace herself as soon as the telltale minigolf course appears on the horizon. Not that she blames her children's ill humor on minigolf; it's just that the course happens to lie 15 combustible minutes from her destination.

This raises a central mystery. If every long car trip were 15 minutes shorter, would children magically lose the impulse to bicker? Logic suggests yes, but empiricism says no.

Perhaps children have a sixth sense, a kind of Squabblers GPS, that warns them when they're a quarter of an hour away -- just as dogs seem to know to go to the window and start wagging in anticipation of their owner's arrival even before the owner's car crunches over the gravel.

We're five minutes away when a child says she wishes we had New Jersey license plates.

"Why?"

"So we don't look like tourists."

"But we are tourists."

To which comes the inevitable riposte: "No, we're not."

Meghan Cox Gurdon's column appears on Sunday and Thursday. She can be contacted at ">mgurdon@washingtonexaminer.com.