Bikers from Australia and New Zealand are on a three-week trek on the historic highway.
They started in Chicago and will take 13 days to check out the sites and scenes. The 53-member group says it is an enjoyable trip.
"The appeal is the open road and the freedom of going at your own pace," says one of the bikers, "being able to see all the old gas stations, museums, and meeting all the people along the way."
The bikers make the trip three times a year.