Which President's son killed by a train?

Benny Pierce

The president was Franklin Pierce. His son was Benjamin Pierce and he was eleven years old when he was killed. Benny was the third child born to his father and his mother, Jane Means Appleton Pierce. Their first son lived for only a few days. Their second son died of Typhus at age 4. The death of her only remaining child put Jane into a deep depression from which she never recovered. She was never able to fulfill the duties expected of a first lady, which were taken over by relatives.