On December 1,1882 the District of Assiniboia comprising of 95,000 sq mi, was formed as a regional administrative district from the entire southern section of the North West Territory covering the southern and central section of the current province of Saskatchewan. Most of it was absorbed into the Province of Saskatchewan in 1905, except for the westernmost quarter, which became part of Alberta.

On February 15, 1881 a charter was granted to the Canadian Pacific Railway with the project to build a railway joining British Columbia to Winnipeg. With the building of the railway came settlers and the first post offices were built along the railway line. By spring of 1882, the railway had been completed to Indian Head and by Dec 1882, the line was completed to the future site of Maple Creek. The development of the railway mail service west of Winnipeg, through the District of Assiniboia as well as the increase in population rapidly followed the progress of the intercontinental railway. By 1885 the population of the District of Assiniboia was 22,083 with Broadview 8367, Qu’Appelle and Regina 9540, Moose jaw 2616, Medicine Hat 732. By 1891 the population had grown to 30,372 with Broadview 13676, Qu’Appelle 6806, Regina and Moose Jaw 7565 , Medicine hat 1316.