IN NEW Orleans, they call Carnival “the greatest free show on earth”—a three-week season of parades full of satirical floats, high-school marching bands, dance troupes and walking clubs. It’s the only place in America that does the pre-Lenten celebration on such a scale. Besides being a fantastic spectacle, Carnival, which culminates with Mardi Gras on February 9th this year, offers a fascinating glimpse into the city's society. Almost every New Orleans resident participates in some way, except for a few grouches who flee when the parading season starts. There are the blue-blood organizations—“krewes,” in Carnival parlance—that have been parading since the late 1800s, when the festival was introduced to the city by French settlers, and whose membership is generally limited to those born into the right (always white) families. There are many less-snooty krewes, which are larger and more diverse. Joining might require an invitation from a friend, membership money and plenty of “throws”: plastic trinkets to chuck from floats, which might total $3,000.

Fat Tuesday is ushered in by the city’s oldest black krewe—the Zulu Social Aid and Pleasure Club—which dons "blackface" and grass skirts for its parade. Its members toss painted coconuts from floats, and leaders vie for top club positions like “witch doctor.” This sendup dates to the white Carnival of the early 1900s.

The activity between the floats is perhaps more intriguing. There are the marching bands: high-stepping, funky, brass-and-drum dominated outfits from the predominantly black city high schools, accompanied by dance teams in revealing costumes and moves to match. Those are interspersed with well-drilled, more chaste bands from the Catholic schools that many New Orleans families have attended for generations. And in between the bands are endless varieties of dance squads and walking clubs that showcase Carnival’s constant evolution. The season is both all about tradition and innovation: new throws, new technological features on floats, and increasingly, new punchlines that riff on last year’s Carnival.

It is this spirit that led to the creation of the 610 Stompers, a wildly popular, large group of middle-aged men, often paunchy and balding, who wear pale blue polyester coaching shorts, luxurious moustaches and bright red sateen jackets while gyrating enthusiastically to hits of the day. Meanwhile women who may feel too old for the high-school dance team but still want to shake their stuff in a Carnival parade now have a range of teams they can try out for. By recently minted tradition, most have risqué names evoking female genitalia.

The explosion of such outfits has made Carnival, which was once largely staged by the aristocracy for the amusement of the hoi polloi, an increasingly participatory event. It might be tempting to attribute this to the narcissism of the “selfie generation.” But some of the city's armchair anthropologists also see the imprint of Hurricane Katrina in 2005, which brought new people to the insular city. Many of them respect its deep traditions, and have found ways to incorporate themselves into those rituals.

“For me, the real fun isn’t what’s on the floats, it’s what’s between the floats – the Rolling Elvi and all that,” says Errol Laborde, a Carnival historian, referring to a group of men who dress as various iterations of Elvis Presley and zoom around on motorized scooters. “A lot of these people are not natives; they’re not bluebloods. They’re part of that new post-Katrina generation, people in their 30s and 40s".

John Jabaley, an actor who moved to New Orleans in 2010 with his family, rides parades as part of an irony-heavy club called the Laissez Boys that zooms around on customised leather recliners as Rat Pack music blares; his wife, an advocate for working people, marches with the Sirens, a dance troupe. He says his young children are already asking to join the Intergalactic Krewe of Chewbacchus, which was established six years ago as a tongue-in-cheek outlet for sci-fi and fantasy fans and has grown into a vast procession that exemplifies Carnival’s new do-it-yourself spirit. “When you see a small group go by, you think you can be a part of it,” he says. “All you have to do is show up.”