It's in. It's out. At last, your guide to necktie etiquette.

Subtle forces are shifting deep in the psyche of the American male. These forces plumb the very depths of identity, class, power, status, and the human mating dance.

They are plumbing in several directions at once.

Someone please call the plumber.

If you believe marketers, imagemakers, bosses like Dilbert's – and other blokes paid to think up ways to tell you, "You're not good enough, but I've got just the thing to fix that" – it has all come down to the common necktie.

In some places (church, restaurants, college) the tie seems to be vanishing alongside the polar ice caps (if you believe Al Gore). Sightings can be especially rare during the hot summer months. But in other places (law offices, stock brokerages, hospitals) ties are reappearing faster than Whac-A-Mole on steroids. "Ties are both coming back and going out at the same time," says Gerald Andersen, executive director of the Men's Dress Furnishings Association in New York. The changes are both real (not imagined) and modified by regional differences (up generally in the Midwest and East; down, for the most part, in the West), he and others say. The personal whims of revolving CEOs can also figure in – no matter what profession.

"Both perceptions are correct," Mr. Andersen says. But with a kind of defiance to those of the now-defunct dotcom era who had all but deep-sixed the necktie in favor of T-shirts, beards, shorts, and sandals, he paraphrases Mark Twain: "The reports of the death of the necktie have been greatly exaggerated."

Of course a guy from the Men's Dress Furnishings Association would say that, some might think. But he's got stats showing where the prediction came from and where it went. The glory days of the tie were in the early '90s, when men, and the women who shop for them, racked up a record $1.3 billion in US necktie sales. But they dipped to half that ($750 million) just a half decade later. That was when "casual Friday" became the mantra, when the nerd-geniuses of Silicon Valley made it a status symbol to thumb their noses at US workplace convention.

Yes, that's how it was? Time to send an e-mail to Wall Street, stomping grounds of this writer's very own brother. "[The '90s was] when everybody figured the way to look businesslike and professional was to look like a dotcom executive wearing a casual shirt and walking shoes like [Apple exec] Steve Jobs, and it was pretty cool since those people were worth $50 million to $5 billion each," writes back Stephen Wood, an investment banker. "All the Wall Street firms and the law firms needed to appeal to the young guns coming out of school, so they adopted the 'business casual code' ('see, we're just as professional and serious about business as you are, Mr. $5 billion Dotcom executive').".

But after the dotcom bust, "the whole trend didn't seem so professional and serious anymore," says Wood. "It seemed like a crock reserved for the rock stars and Hollywood types."

By 2000, though, neckwear started coming back – thanks to Regis Philbin, with dark tie on dark shirt, hosting oodles of episodes of "Who Wants to be a Millionaire" on ABC. And after the 9/11 attacks in 2001, a shocked nation went back to basics – yes, even with its wardrobe.

Since then, say experts, the tie look – overall – has rebounded. Maybe not to its earlier height, but sales are at least well over the $1 billion mark as of this year.

Although it's possible that some of these tie purchases usually stay in the closet, reserved only for special occasions, others are convinced the change is for real. "It seems pretty clear there is a movement to start dressing up again, and ties are part of that," says Joseph Rosenfeld, an image consultant with the Association of Image Consultants International (AICI). Think individualized choices – bold colors from pinks to oranges – with radical designs, he says. Thin is back in, as are ties that cost more than $100.

Employers are trying to bring back the tie, says Colleen Abrie of AICI, because "no doubt you perform better when you feel more professional looking."

That's how Matt Alexander, who works at Wellington Management in Boston, sees it. "Financial is a place for ties," says the client administrator, who is required to wear a necktie in the office.

More and more employers, it seems, were walking into work on casual Fridays and not liking what they saw. Many lost clients who entered dressed-down offices. The globalization of trade has also prodded Americans to spruce up their image, since Europeans and Asians tend to place a high value on a professional interchange.

Daryl Johnson, who works at GMO LLC, an investment management firm in Boston, has seen these forces firsthand. Although his office has adopted business casual year round, and he thinks it "contributes to a better working environment," the exception is when he and his colleagues conduct interviews or meet with clients. Then, "business formal is worn ... to show our respect," he says.

Sociologists, image consultants, and style mavens say the ups and downs are all a part of a bigger pattern: On roughly 20-year cycles, the open-collar look comes into vogue.

Recall ascot-coiffed Cuban bandleader Ricky Ricardo on "I Love Lucy" in the '50s, followed by the button-down Ward Cleaver ("Leave It to Beaver") and Robert Young ("Father Knows Best"). In the '70s, John Travolta brought the opencollar back ("Saturday Night Fever") before it died alongside discomania. In the late '80s, casual returned (with a lag to catch up with Crockett and Tubbs of "Miami Vice").

Today, there are still huge pockets that have defiantly stayed with the casual style. "[Ties are] uncomfortable, restricting, and serve no practical purpose," says Michael Saffran, a media-relations specialist at the Rochester Institute of Technology in New York. Faculty there don't wear ties, and many students have probably never seen one, he says. Things have gotten even more casual over the past five years, to the point where he has worn one only once in the past 12 months. "I had been hoping to make it a full year without wearing one, but I broke down and put on the 'noose' for a formal awards dinner this past spring," he says.

Recently a friend told him that wearing a tie gave him a sense of empowerment.

"My response to him (and to anyone who feels similarly) is this," says Mr. Saffran. "The only one being empowered are the people you're trying to impress by wearing a necktie."

• Ashley Twiggs contributed to this report in Boston.