It’s been said that America lost a good deal of its national innocence the day President John Kennedy was killed in 1963. There is more than passing evidence that such things as ethics, morals, civility, decency, maturity and willingness to accept responsibility for one’s own actions have deteriorated since then.

After all, the Kennedy killing was one of those crimes that could not happen in the minds of many. Was nothing sacred anymore? It was a shock we are still paying dues to overcome, and the sad thing is that there is evidence we have lost ground rather than regained any.

Changes, severe and subtle, have been occurring in the past four decades that understandably have many reflecting on “the good old days,” even if our memories deny the fact that many times they weren’t all that good.

One of the troublesome nuances of deterioration that many have noticed is the long-revered high school prom, which once was an occasion for delight, celebration and enjoyment for most youngsters and their families. Girls and boys arranged dates, males scrambled to scrape up enough money for corsages and begged to borrow the family vehicle for the occasion.

“Dressing up” was a big deal; parents could beam with pride about how well some of their teenagers “cleaned up,” at least for one night. Oh, there would be occasional problems of behavior by overzealous youths, but generally they were not of a community-jolting or budget-shattering nature.

What has happened in recent times is discussed in a recent issue of Time Magazine. Titled “Barred from the Prom,” the piece describes how so many schools have been forced to impose prom regulations that nobody ever thought of in past times. There are screenings for alcohol abuse at the door, drug-free pledges and, get this, criminal background checks on dates whose names have to be registered beforehand.

Some schools have put age limits on male dates, such as 20. In some instances this has prevented girls from having young military combat veterans admitted, even if the two dated before the military service began.

Consider this. A Tennessee high school set an age limit for its prom this year after a former teacher who had gone to prison for having sex with a pupil was arrested for contacting the boy again. A Texas teacher was fired for asking to take a student to the prom.

Six students on Cape Cod, Mass., were upset earlier this month when their dates were barred from the prom after criminal background checks turned up past misdemeanors such as drinking, DUI and marijuana use.

Virtually everywhere, efforts are made to have special parties with unique inducements, such as the auto giveaway in Lawrence, to get youngsters to take part in sane activities and avoid tragedy. It’s a way to keep youngsters safe, but it’s somewhat sad that it has to be this way.

The 17- and 18-year-olds in our midst regard, quite naturally, prom occasions as a rite of passage and resent being “treated like children.” But most of the participants still are that, and too often act like it, no matter how many ways they attempt to rise to “adult” status. It’s discouraging that so many “adults” like the errant Tennessee teacher also fall short in the maturity department.

Mark down the high school prom as another of those issues of innocence that began to degrade some time ago and doesn’t show much promise of growing up again.