Dear Zoe by Philip Beard
This Story is told through the eyes of Tess DeNunzio. She is writing a journal to her younger sister, Zoe, who was killed on 9/11. But, instead of dying in New York, she was killed just outside her house by a hit-and-run driver. Tess mourns her death by writing a book to her and telling he all the things that have happened since she's been gone.