Where is the location of the book when Hannah is Hannah and when she is Chaya?
In Jane Yolen's book The Devil's Arithmetic, modern-day Hannah is from New York (the city of New Rochelle) as she tells Gitl and Schmuel repeatedly when she awakens in their house the following morning as Chaya. Hannah becomes Chaya when, as part of the Passover ritual, she opens the door to let in the prophet Elijah. She sees upon opening the door that there is an unfamiliar scene, and when she turns around, the transformation is completed.
Now Chaya, she is in a Polish shtetel (village) in the year 1942. When they are taken by the Nazis, they are in the village of Viosk for Schmuel and Fayge's wedding. The concentration camp they were taken to is in the area of Donavin, Poland.
At the end of the novel, she is transported back to modern-day New York (probably in the 1980s since the book was written in 1988).