In 1863, Edgerton was appointed, by President Abraham Lincoln, to be the Chief Justice of the Territory of Idaho. His salary was to be $2,500 a year (about $34,000 in 2009). He left with his wife, his children, his niece, Lucia Darling, his nephew, Wilbur F. Sanders, Sanders' wife, Sanders' children, a family friend, Henry Tilden, and a young woman named Almarette Greer. Edgerton's group first travelled to Cleveland, Ohio, by train, they then traveled, by boat, across Lake Erie, continuing, by train, to St. Joseph, Missouri, they then travelled, by steamboat, to Omaha, Nebraska. They then bought their provisions, and began their trip on ox-drawn wagons. The party was met by good weather, and no bad confrontations with Native Americans. The group stopped at Chimney Rock, to visit. They then started off again, on their trip. One incident that did happen was when Edgerton fell from one of the wagons, and was almost crushed by one of the wheels. The group arrived at South Pass, in August 1863. After arriving in South Pass City, Edgerton received a telegraph message saying that the capital of the Territory of Idaho had yet to be decided. On August 15, as the group was heading west, a man arrived with a telegraph message saying that the capital of the Territory of Idaho was to be at Lewiston. The message was welcome news to the group, but knew that to get to Lewiston, before the snows, would be difficult. As the group descended the western slopes of the Rocky Mountains, it was discovered that Mary Edgerton was pregnant. In September, the group arrived at the trail, beginning at the Blackfoot River. Edgerton realized, that it would not be possible to make it to Lewiston, before the snows. The group then changed its course for Bannack. The party crossed the Snake River, by ferry, on September 6. After crossing, they met Sheriff Henry Plummer. This would not be the last meeting between Edgerton and Plummer. The group continued, and crossed Monida Pass. The group finally made it to Bannack, on September 16.