On the back it says "Thelma New York."
I'll go out on a limb here and guess her name was Thelma. What's the rest of the story?
In my mind this was one of several shots taken in a photobooth to send to a young man she'd met. She wanted him to remember her, but didn't want to appear too forward so she just put "Thelma New York" in hopes he would remember her.
Her smile makes me think of Johnny Mathis which has me thinking of this song. I'd like to think that Thelma found the boy who loved her even if he wasn't from New York.