Michelle Obama probably has a long list of things she’d like to be remembered for—like her initiatives to combat childhood obesity and promote higher education—before she’s remembered for her sense of style. But with great responsibility comes great clothing, and the First Lady will certainly go down as the most fashionable woman in the White House since Jacqueline Kennedy.
Obama is known for choosing the patterned dress over the more subdued pantsuit, for baring her toned arms and—perish the thought—even wearing shorts. And there are some who argue that the choices she makes transcend personal expression and petty analysis and carry a certain amount of cultural significance.
“For some reason in this country there’s this false notion that style and substance have to occupy two separate worlds,” said fashion journalist Kate Betts in an interview with CNN, “and I think she’s proving that that’s wrong.”
See Michelle Obama's Best Outfits of 2014
According to Betts, author of Everyday Icon: Michelle Obama and the Power of Style, Obama’s style choices convey comfort (the occasional flats), confidence (feminine florals) and relatability (she shops at J. Crew). Her effortless looks, Betts wrote in the New York Times, make it “hard to imagine that there had ever been any dress code for her position.”
As these photos by LIFE photographers show, there hasn't exactly been a dress code, though styles have historically erred on the conservative side (in terms of hem lines, not party lines). The first ladies' fashions have both evolved with popular trends and helped to inspire them. Furs, seen on Eleanor Roosevelt, Bess Truman, Mamie Eisenhower and Lady Bird Johnson, have fallen out of favor in recent decades. Hats, from Truman's rather vertical design to Kennedy's pillbox style, are infrequently sported by recent first ladies. Leather, with the exception of Nancy Reagan, shown in 1968 before her First Lady days, has been far from a staple, whereas the simple pearl necklace continues to be a timeless, nonpartisan classic.
While Kennedy's style was described by LIFE in 1961 as having "an almost deliberate plainness," Obama does not shy away from a hint of flourish here and there. But she's certainly not the first to indulge in a bit of flair. When working with a designer on her dress for the inauguration in 1953, Mamie Eisenhower had a few extra requests. "She specified pink and asked for some additional glitter." Because even the White House—no, especially the White House—can use a little sparkle now and then.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.