How to Look for Ruts and Swales
Santa Fe Trail wagons left a mark on the landscape and can still be seen today from the ground and the air.
From the air:
http://www.santafetrailresearch.com/spacepix/0ur-space-link-page.html
http://www.boothill.org/santa-fe-trail-rut-site/
From the ground:
https://safe.oncell.com/en/77-ralphs-ruts-and-kern-ruts-131065.html
https://www.nps.gov/fols/learn/historyculture/santa-fe-trail.htm