http://www.flickr.com/photos/mfspeccoll/4903406580/in/set-72115762474243...

This poster's purpose is to appeal to the American populace for funds for the Red Cross. It is an annual campaign called "The Roll Call" which was usually held every year around Christmastime.  The poster reflects two women, one dressed as a nurse and the other one in a classically draped garment.  Obviously, the Red Cross nurse is pointing at the viewer to give money and join in the membership while  the other woman is also a model to persuade. Bt who is she? She is the  personification of the United States of America, then known as "Columbia". Columbia was a well known symbol for the goddess America prior to and during WWI. She is wearing the white draped garment and blue sash and has a "liberty" cap on her head.  Columbia was displaced as the female symbol of the U.S. by the Statue of Liberty in the 1920s.

The Roll Calls were annual appeals to generate funds for the  Red Cross during WWI.  It cost $1 dues.  Columbia is seen joining and signing her name to the "Roll" as an example to all others to do the same as citizens of the U.S.A. Bold colors of red, white and blue help to make this a traditional patriotic poster.