After prominently practicing law there, he moved to West in 1861, first to California, then to Auburn, Oregon, where he engaged in the transportation business between that town and Placerville, which would become part of the Idaho Territory in 1863.

He moved to Placerville, and then Rocky Bar, in 1863, and was elected by Boise County as a Republican to the first session of the Idaho Territorial House of Representatives.

[4] As his four-year term ended, Kelly was renominated by President Ulysses S. Grant on January 17, 1870, and was confirmed by the senate a week later.

[2] After his judicial service, which was based in Lewiston, Kelly relocated to Boise, and on January 2, 1871, he purchased the Idaho Statesman from James Reynolds.

Under his leadership, it strengthened its position as the state's leading paper, and he sold it in 1889 to the newly formed Statesman Publishing Company.