Inside the Life of Michelle Obama

If Barack Obama comes out the victor on Election Day, he will not be the only one making history. His wife, Michelle Obama, would become the first black first lady in history.

Lisa Mundy, author of a new biography on Michelle Obama, told "Good Morning America" that for the Illinois senator's wife, moving seamlessly into new worlds is, by now, second nature.

"I think Michelle Obama could legitimately argue she has more friends of more races than most Americans do," Mundy said.

Obama grew up in a working-class black neighborhood in Chicago but attended a racially mixed magnet high school.

"I actually found a photograph of her in a high school shot for the National Honor Society where she is standing by a white classmate, Kristy McNulty, and at the last moment before the shutter went off she reached out and put her arm around Kristy's shoulder," Mundy said.

When she talked to McNulty, Mundy learned that Obama could always move easily between social groups.

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When Obama attended Princeton, whose demographic was heavily white, the experience was more profound.

"She writes in her thesis that was when she first realized she was black," Mundy said.

Rather than avoid the issue, Obama focused her senior thesis on how black students groomed to move into a whiter world could stay connected to their culture.

After graduating from Harvard Law School, she was welcomed at the tony Chicago law firm of Sidley Austin. She was one of a few black associates.

There, she met a young Barack Obama and discovered they shared a passion for community service.

But like any marriage, there were struggles.

In Barack Obama's book "Audacity of Hope," he writes that there was a time in their marriage when they were barely on speaking terms.

Work seemed more and more of a burden so Michelle Obama cut back on her career and enlisted the help of her mother.

"She has said there have been times when she had considered being a stay-at-home mom," Mundy said. "I think, like many women, once she had children, the workplace was still important, but it wasn't all important."