First lady Michelle Obama turns 47 on Jan. 17, and to mark the occasion, we're taking a look back through her fashion highs and lows.

From her signature nipped-waist dresses and embellished cardigans to those shoulder-baring gowns and bold graphic prints, Obama has been a force of style to reckon with since joining her husband on the campaign trail in 2008.

Effortlessly, she is able to mix American designers such as Thakoon, Isaac Mizrahi and Michael Kors with affordable wears from Talbots, J.Crew and Banana Republic. And we were pleasantly surprised when the first lady made her first foray into vintage wearing a black lace design in a '50s silhouette by late American designer Norman Norell during the holiday season.

By flaunting these brands' fashions, Obama generates a cool $2.7 billion in sales -- and that's not the only impact in fashion she's made. For example, her choices create trends and ever since she added a fresh, flowered pin to her sheath frock, she's spawned an army of chic copycats.

Peruse our gallery of the first lady's fashion choices and don't forget to check out the style evolution of foxy 64-year-old Tina Turner.