The white space around her was for writing the correspondence. You could not write the message on the same side as the address. The back of the postcard was for the address only. So it has an undivided back, which means there is no dividing line between the address side and correspondence side, Postcards with an undivided back were made between 1900 and March 28, 1907. That's how we know the approximate age of this card even though it has no postmark.