When was st chistopher born and why is he saint of travellers?

St. Christopher just fell off the rolls of Saints. He's been determined to not have ever lived. However, he is the most popular. The story is interesting though, including the one in which he was crossing a river when a child asked to be carried across. When Christopher put the child on his shoulders he found the child was unbelievably heavy. The child, according to the legend, was Christ carrying the weight of the whole world. This was what made Christopher patron saint of travelers and is invoked against storms, plagues, etc.. His former feast day is July 25.