As the dog days of summer ­meander to their end, where have all the college kids gone? They’re mostly back at school, weeks before Labor Day, during a time most of them can be banking money for the school year.

The mid-August campus arrival date is theoretically there to get the student situated for the start of school. Register for classes, buy books, party with dorm-mates. But in 2019, you can register for classes online and order your books to your doorstep. Why are colleges cutting into valuable work time for their students by calling them back to campus ­before Labor Day?

Summers are traditionally a money-earning opportunity for college kids. Sure, some loaf around, but the smart ones work to avoid crippling student debt or to have pocket money throughout the year. We have an ever-ballooning student-loan problem in this country: Why not give students a longer summer off to earn their dough for the school year?

Schools that do start post-Labor Day give their students an advantage to keep working until the end of the season.

Rory, a 20-year-old cabana boy at a beach club on Long Island, whose college starts back up in September, told me that it’s a benefit to him that he can continue working for an extra few weeks before school starts. Some of his co-workers travel long distances to school and then back again to finish out the summer season — and collect the end-of-season tips they count on.

It’s not just the service industry that’s affected by the early college start date. Bills have been introduced in Ohio, Georgia and other states to delay the start of the school year until after Labor Day so farms have enough workers.

Farmer Karen Burwinkel of Burwinkel Farms wrote in support of one such bill in The Cincinnati Enquirer in 2017: “The early start to the school year has a bigger impact than many realize. Our farm, for example, has been forced in recent years to shut down our harvest season early because of the anticipated loss of labor.”

The real issue is that colleges don’t see themselves as being fundamentally related to employment — but students who shell out tens of thousands of dollars to attend higher education surely do.

Many colleges don’t seem to real­ize, or care, that kids who ­attend might need a job to be able to afford tuition. The life of the mind matters. So does the wallet. For most students, moreover, college is a steppingstone to better job prospects, not just learning how to pronounce Nietzsche and Solzhenitsyn correctly.

A more realistic college model must take periods of work into account. It doesn’t have to just be summer jobs, either. My alma mater, Northeastern University, is a five-year school that incorporates students taking whole semesters, and sometimes more, off from school to go work in jobs in their chosen fields.

When students graduate, they have a real résumé of employment. And there’s the added benefit of finding out before you graduate that the field you thought you wanted for your career isn’t for you.

Colleges have to admit there is a problem, one that can’t be solved with the typical school guidelines allowing students to work 10 to 15 hours per week. But so far, they seem to mostly bury their heads in the sand.

In April, New York City’s Department of Consumer and Worker Protection announced a public-awareness campaign about student-loan debt. Ads warned young people that “financial aid is not free money” and “student loans are real debt.”

It’s a national crisis. People are plunging themselves into sometimes insurmountable debt to get a degree. It shouldn’t be the role of city governments to ­explain that loans taken out for schooling are “real debt” — it should be the role of the schools themselves. And that explanation has to come with solutions for ­allowing students to work while they go to school.

Pushing back college start dates until after Labor Day would be a good start — and a winner for all.

Twitter: @Karol