Vintage French enamel Saint Christopher keychain, c. 1960's.
 
St. Christopher -  the patron saint of travelers. 
There are several legends about him 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.