This shows four Red Cross uniforms, left to right: Motor Corps driver’s skirt and tunic; Motor Corps driver’s uniform; Motor Corps driver’s overcoat; Foreign Service uniform. The women, depending on what they did and where they worked would wear these.
This 1918 picture from the National Archives shows a cheerful American Salvation Army girl rolling pie crusts for men of the 26th Division in France.
The Colonial Dames Collection includes this uniform worn by an army contract surgeon. Women doctors were not allowed to join the Army Medical Corps. Only the Army Nurse Corps accepted women. But the army did issue contracts to a small number of female physicians, who remained civilians even though they worked in uniform.