The story
Originally (from 17th c.), to leave in the dust meant to abandon or leave something/someone behind - literally or figuratively on the dirt ground. In modern usage (since late 19th c.), the sense has shifted to one about being overtaken by a competitor, the allusion changing to being left in the airborne dust that has been kicked up by a faster runner, horse, or vehicle.
First known use, by meaning
- from late 19th c. To completely overtake a competitor.
- 17th–20th c. To abandon; to leave behind.
Etymology from Wiktionary, CC BY-SA 4.0.