According to WWD Michelle Obama’s Vogue issue was a certified best seller:

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The frameworthy issue sold 560,000 copies on the newsstand, 1,000 more copies than their most recent best selling September issue.
WWD writer Stephanie D. Smith says, “The First Lady has been featured on the covers of Ladies Home Journal, More, Ebony, People and Us Weekly, however sales for those titles have varied. (According to Advertising Age, sales for the September issue of Ladies Home Journal with both her and husband President Barack Obama on the cover were 21 percent smaller than the year prior.) Obama is also featured on the April issue of O, The Oprah Magazine, along with Oprah Winfrey, and the May issue of Essence with her mother, Marian Robinson.