Why is Sal afraid of car accidents and death in Walk Two Moons?

Sal is scared of car accidents and death because her mother died in an accident.
Many of Sal's fears come from the death of her mother and the experiences she's had in her life. The fear of death and car accidents are particularly bad because she knows how quickly you can lose someone if there's an accident on the road. A few times in the novel, she actually prays out loud for there not to be any accidents during their vehicular travels.
On the first day of her trip, she actually prays for 30 minutes. She says that she prays for safety because she is specifically scared of cars and buses. Her mother was on a bus when she died. It swerved and most of the passengers were killed when it went off the road. During the book, Sal is going with her grandparents to visit her mother's grave.