Willow Run by Patricia Reilly Giff

Sequel to Lilly's Crossing, this does stand alone. What would you do if your whole life is turned upside down? Meggie's family moves to Michigan so her father can work in the bomber plant. She has a nice home in New York, but lives in quickly-built worker housing. Her brother is off to war and her German American grandfather stays back in New York to look after things. Thrown into a group of other transplants, she learns that life is what you make it and that friends don't have to share your background, just your present.