In 1881 Macdonald arranged Dewdney's appointment as lieutenant governor of the North-West Territories. Dewdney resigned his seat in the Commons, but remained Indian commissioner during his term as lieutenant governor, which lasted until 1888. Responsible government had not yet been granted to the North-West Territories, so Dewdney was the Territories' head of government and not a mere figurehead. Perhaps his most notable decision in office was changing the territorial capital from Battleford to Regina in 1883.
After his term as lieutenant governor, Dewdney was again elected to Parliament and served as the member for Assiniboia East (now southeastern Saskatchewan) from 1888 to 1891. During this period he also served as minister of the Interior and superintendent of Indian Affairs.
In 1892 he was again appointed lieutenant governor, but this time for the province of British Columbia. He served in this post until 1897.
Dewdney was originally employed as a railway surveyor, and supervised the survey of New Westminster.
From 1868 to 1869 EdgarDewdney became active in Colonial politics, representing the electoral district of Kootenay in the Legislative Assembly of British Columbia.
In 1881 Macdonald arranged Dewdney's appointment as Lieutenant-Governor of the Northwest Territories.
Dewdney promoted the further subdivision of agencies, the appointment of additional personnel, such as inspector Alexander McGibbon*, to ensure closer supervision of the Indians, the creation of individual farms on reserves to strike at the heart of the tribal system, and the establishment of more industrial schools.
William Dell Perley, the mp for Assiniboia East, was appointed to the Senate and Dewdney was elected to the House of Commons in a by-election on 12 Sept. 1888.
Dewdney was a well-known figure by then and his status as a pioneer in the province made him a popular choice as the crowns representative, although his wifes snobbery would cause occasional irritation.