It's not an uncommon phrase. "Let's ask God for traveling mercies on this trip." So I had to ask. What do we mean by "traveling mercies"? I mean, think about it. Mercy means justice suspended, so to speak. It is a punishment withheld. What does that have to do with traveling? Grace, on the other hand, is an undeserved kindness. "Traveling grace" makes sense. We would like God to protect us on the trip -- a kindness we don't deserve.
I have decided, in reflection, that my objection is to be rescinded. It is a product of a standard view we all carry around, whether or not we admit it, that we're basically good people. Christians especially think "I deserve ___" and fill in the blank with good things. After all, we're God's children, God's special chosen, God's adopted. What's "mercy" got to do with it?
The truth is simple. When Adam ate the fruit in the garden, had God terminated human life at that moment He would have been perfectly just. Ever since then, if God were to terminate anyone at any time, He would be perfectly just. We are sinners. Christians have been declared just by the work of Christ on the Cross, but we are sinners. We know this because none of us has yet arrived at perfection.
So if God were to kill me on a trip across country and give me eternal life on the other side of my death, it would be great mercy and grace. Real mercy, then, is when I survive another day. Real mercy is when I take another breath. And the fact that we returned from our trip safe and sound is indeed "traveling mercies".