She's not the first woman to head a global corporation.
Ginni Rometty runs IBM, and Indra Nooyi heads PepsiCo. Don't forget Ursula Burns at Xerox and Meg Whitman at Hewlett-Packard. There's Marissa Mayer at Yahoo.
Still, when Mary Barra emerged on Tuesday as the new chief executive of General Motors, the announcement felt historic. Next month, the 51-year-old daughter of a GM factory worker will succeed retiring Dan Akerson as leader of the biggest U.S. automaker.
The automotive sphere has been seen as a guy thing since the first oil-splattered cars started rolling down dirt roads in the late 1800s. Even now in Saudi Arabia, women risk violence or arrest just for sitting behind the wheel of a car.
But in Detroit, Barra leapt ahead of men such as Mark Reuss, president of GM North America; Dan Ammann, chief financial officer; and Steve Girsky, vice chairman.
"It is remarkable because the auto industry has always been such a male-dominated industry," says Jerry Jasinowski, an economist and past president of the National Association of Manufacturers.
Just 1 in 5 workers in the auto industry is a woman, and a mere 4 percent of CEOs at all major U.S. companies are female. So Barra's promotion is a big deal. On the other hand, auto analysts say her elevation should not come as a surprise to anyone at GM because her career path has been so steady.