In the 1890's a little special something might have accompanied the US Post, coast to coast and north to south.
Perhaps I should say a special someone. His name was Owney, and he was a stray brown dog that showed up at the Albany Post Office in 1888. In a way, he never left. He was so fond of something about the mailbags that he followed them everywhere, even onto the Railway Post Office trains. He'd mail himself back to Albany, often with a few commemorative tags and medals on him. Over the years he amassed quite a collection, and a special harness was made so that he could wear those tags all over.
Speaking of "all over," in 1895 Owney went around the world, through the continental US through Asia and the Middle East before being delivered safe and sound back to Tacoma, where he'd started.
In 1897 Owney was old, sore and cranky, and was put down. But he's still on duty at the Smithsonian Institution, nicely preserved. His wandering spirit also lives on in the teaching program he inspired, in which a toy Owney travels from one elementary school to another, thereby making kids curious about geography: "Where's Owney been?"
(He also made "Best Animal Monument" of 2008 in the Washington City Paper!)