Traveling mail is a form of 'snail mail' which multiple people contribute towards. The most common form of traveling mail is a postcard, that is sent from person to person to sign.

Unlike a traditional postcard, it is always sent in envelopes, and can take up to a couple of years to return home. When it does eventually find its way back, it's worth the wait. Each piece of mail has a journey across the world to share.
My Canadian pen pal sent me this postcard, almost fully covered in signatures and pictures from the snail mailers who passed it along. I wish it was dated.
I love this postcard's wandering path: California to Nebraska, back to California then to Michigan. It returned back to California before heading to Pennsylvania. It was sent to another city in PA before finding itself in Ontario, Canada. It is now with me and it is my daunting task to find its next destination. Suggestions/offers anyone?