In 1912, a conference of businessmen from South Dakota met to build a better road between Ipswich and Aberdeen, South Dakota, leading to the development of the Yellowstone Trail, which stretched from "Plymouth Rock to Puget Sound." As transportation transitioned from railroad to auto travel, it became the first transcontinental highway across the northern United States. The route originally followed existing wagon roads, but changed over time as new roads were built. Through Prairie County, it passed from Mildred to Fallon to Terry and westward to Miles City.