FILE - In this April 1919 file photo, two female members of the U.S. Navy's Yeoman unit pose in their chin strap hats, tie, jacket and long skirt in New York City during World War I. World War I was the first time in the nation's history that women were officially attached to branches of the U.S. military and more than 30,000 women served in uniform, mostly as nurses or switchboard operators. Thursday, April 6, 2017, marks the 100th anniversary of the U.S. entry into World War I, and some of the innovations that were developed or came into wide use during the conflict are still with us today. (U.S. Navy via AP)