The saint who is the patron of travelers and is often shown carrying the Christ child across a river is Saint Christopher.
The best-known story comes from medieval legend, especially the “Golden Legend.” Christopher is portrayed as a physically imposing man who wanted to serve the greatest possible ruler. After converting to Christianity, he helped travelers cross a dangerous river. One day, he carried a child who became increasingly heavy during the crossing; the child then revealed himself as Jesus Christ.
That episode explains the saint’s distinctive Western iconography: a giant or tall figure with a staff, carrying the infant Jesus on his shoulders through flowing water. Because the legend portrays him helping travelers, Christian communities adopted him as a patron of travelers and transportation. Small images or medals of Saint Christopher have consequently been carried or placed in vehicles.
The story is devotional legend rather than a securely documented biography. Accounts place Christopher’s life broadly between the mid-3rd and early 4th centuries, and traditions vary across churches. He should not be confused with the archangel Michael, Saint Jude, or Saint James, none of whom is identified by this river-crossing image.