American Muslim Women Unveil, And Explain Why : NPR.
There are about 1 million Muslim women in America; 43 percent of them wear headscarves all the time, according to the Pew Research Center. About 48 percent — or half a million women — don't cover their hair, the survey found.
The split between women who've covered and women who've never done so has existed for decades. But now a generation of women is taking off the headscarf, or hijab.
See also: http://www.npr.org/2011/04/21/135413427/lifting-the-veil