I love poetry! My first thought was could the modern update version be an Airstream and who writes poetry nowadays?
200 years ago which coincides with the Lewis & Clark expedition, man could only average 3 mph travel. Also, the mother of all earthquakes occured almost 200 years ago, not in California, but near the confluence of the Mississippi and Ohio Rivers. I'm sure that knowledge influenced the "One Hoss-shay".
2015 Sprinter Class B Camper Van
(Former 1971 vintage Airstream Owner)