Jacqueline Kennedy Onassis
Jacqueline Kennedy Onassis in 1961

During her 1961 official visit to Paris, Jacqueline Kennedy sported an Alaskine (wool and silk) suit created by Oleg Cassini and pillbox hat created by Roy Halston Frowick.

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It's no coincidence that two U.S. first ladies made our list, and you could argue that Michelle Obama owes credit to one of her predecessors: Jacqueline Kennedy Onassis. Affectionately known as Jackie O, she was always impeccably dressed. Whatever the occasion or stage of life, we could count on her to lead the fashionable way.

We still recall with great fondness her pill box hats, ladylike suits and A-line dresses, which seemed to capture America's affinity for a stylish first lady. After her White House reign ended in the 1960s, she traded more conservative campaign clothes for a refined look befitting the era: wide-leg pantsuits, silk head scarves and her signature oversized, round sunglasses. Then Jackie O moved on to a Mediterranean look that sported elegantly casual gypsy skirts and a smattering of equally casual jewelry. It wasn't the last of her memorable fashion trends, but it remains an example of the tone she always set: relaxed, yet elegant.