The notion that Jackie Kennedy was, and remains, a fashion icon is today such a commonplace that it's difficult to fathom, five decades later, just how enormous her influence really was the late 1950s and early 1960s, when she and JFK briefly held — or rather owned — the national spotlight. In fact, one simply can not render a complete picture of American style in the latter half of the 20th century without a bow to Paris-born Oleg Cassini and the designs he created expressly for Jacqueline Lee Bouvier Kennedy.
To this day, it's pretty much impossible to see a pillbox hat and a perfectly simple, chic dress and not think of the First Lady.
But perhaps the key to the enormous popularity of Jackie Kennedy's style among women, from 18-year-olds to octogenarians, was not the sheer elegance of her style, but the sense that, while the president's wife was unquestionably a great beauty who carried herself with an easy, enviable grace, she was also someone that millions of people liked. She seemed approachable, friendly, kind — even when she was rocking an original Cassini creation at a White House reception or a black-tie gala.
It's no wonder, then, that countless businesses and industries, from neighborhood hair salons to major clothing manufacturers, wanted to get in on the action, emulating and celebrating the "Jackie look." But in 1961, when one manufacturer decided to create mannequins modeled on both Jackie and president-elect Kennedy — well, then it got a little weird.
LIFE magazine, meanwhile, took the hoopla (which it helped to create, after all) in stride, writing in its January 20, 1961 issue:
Jackie Kennedy, even in fashion sculpture, is a remarkably recognizable version of Jackie in the flesh. Her look and style are setting a national pace.
College girls copy it casually, suburban matrons faithfully. Millinery shops are being fortified with the largest collections of pillboxes in history. Fashion ads twinkle more mischievously with Jackie's unmistakable wide eyes. Her bouffant hairdo is becoming a by-word in beauty salons. All in all, the shy, beautiful First Lady's fashion followers are building up quite a bandwagon.
Jackie's smoothly simple look in clothes is achieved by an almost deliberate plainness. It is an elegant and expensive style from pillbox to pumps and it can be inexpensively copied.
The Jackie bandwagon started before the Wisconsin primary as American women began to look admiringly at Mrs. Kennedy's sophisticated simplicity. It hit a new high last week when 217 fashion editors were exposed in New York to a flurry of mannequins, ads and style shows. The First Lady's newly appointed designer, Oleg Cassini, announced he would keep up the Jacqueline look in a continuing series of designs.
Credits: top, Paul Schutzer; bottom, Yale Joel
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter @lizabethronk.