The opening show of fashion’s month of catwalks was not on the official schedule, but Viola Davis and Cynthia Erivo were snuggled on to celebrity-packed benches in a cathedral-sized marble hall where tapestry-hung walls and a gilded coffered ceiling framed a view over lower Manhattan.Ralph Lauren, 86, took his bow at the end of this women’s wear show casually dressed in a varsity jacket spelling out New York. In an industry obsessed with youth and novelty, Lauren is more relevant than ever in his ninth decade.He described the show as “irreverent”. Velvet evening wear was burnt out to show a little skin beneath. There were shredded, low-slung jeans – take note, jeans-wearers everywhere – and a wink to the extra-wide ties that started his empire 59 years ago.The spray-painted brocade gowns and lush embroidered evening coats on this catwalk will be giddily expensive, but the energy propelling the brand comes from a much broader audience.Ralph and Ricky Lauren. The designer took his bow at the end of this show casually dressed in a varsity jacket spelling out New York. Photograph: Dia Dipasupil/Getty ImagesGen Z has rediscovered Ralph Lauren, and its Polo shirts, rugby shirts and baseball caps are cool again, a renaissance that shows up emphatically on the balance sheet. This year the fashion house reached its highest ever annual revenue figure of $8.1bn (£6bn) – a rise of 15% on the previous year.Ralph Lauren has a genius for marketing that feels like mythology. The 1920s-coded cocktail dresses nod to Gatsby’s lawn; the denim to cowboy ranches. There are college jocks and Upper East Side socialites. Born Ralph Lifshitz, the son of Jewish immigrants from Belarus, the designer has invented a fantasy America, borrowing from English aristocracy and from classic westerns; from Native American craft and Waspish New England; from country clubs and jazz clubs.He has taken the contradictions of the US – old money and the frontier, east coast establishment and wild west freedom – and made them look as if they belong together.This world is not real, but it is visually coherent, and has proved to be universally seductive whether you are shopping for a baseball cap or a ballgown. It is this sleight-of-hand – selling the fantasy, not the actual product – that has enabled Lauren to remain aspirational to the 1% while making a ton of money in the malls.In a statement, Lauren described his latest collection as “the freedom and fun of creating a style that is truly personal”. Experimental fabric techniques gave the impression of a design studio that still knows how to have fun.skip past newsletter promotionafter newsletter promotionLauren described his latest collection as ‘the freedom and fun of creating a style that is truly personal’. Photograph: Caitlin Ochs/ReutersGrand gowns were laundered with a “spritz and tumble” method that gave a louche rumple to their glide along the catwalk. Lauren was this week announced as a nominee for American menswear designer of the year, and his tailoring heritage showed up in two sharp trouser suits, tailored for women in an Italian menswear workshop.The swagger of the show was a fitting curtain-raiser to a New York fashion week that opens with more confidence than in recent seasons, as designers gravitate toward a US market that is a bright spot in a troubled global luxury industry.Fellow grandee Tommy Hilfiger will stage a show at the Plaza Hotel, with Michael Kors setting up his catwalk at the Museum of Modern Art. The Diane von Furstenberg brand returns with its first show in a decade when new designer Henry Zankov shows his debut, and London-based, New York-born Conner Ives makes his home-town debut.