Alberta provincial electoral districts are currently single member ridings that each elect one member to the Legislative Assembly of Alberta. There are 87 districts fixed in law in Alberta.
The original twenty five districts were drawn up by Liberal Member of Parliament Frank Oliver prior to the first general election of 1905. The original boundaries were widely regarded as being gerrymandered to favor the Alberta Liberal Party. Every boundary redistribution since 1905 has been based on the original boundaries, with districts being split or merged.
From 1905 to 1926 with only a few exceptions each district elected a single member on the First Past the Post system. Calgary and Edmonton as well as Medicine Hat were elected on a plurality block vote, where each voter had as many votes as candidates were elected.
There have also been a couple of cases where members were elected at large, and did not represent any districts.
From 1926 to 1955 members in Calgary and Edmonton were elected in Single Transferable Vote super ridings that had five to seven members. Outside of the two cities one member was elected under the optional system, with vote transfer taking place only if one candidate had less than 50% of the vote. There were no district changes between 1926 and 1940.
With Alberta in a population boom in the fifties and Calgary and Edmonton growing, single transferable vote was becoming too complicated, with vote counting taking days before any results could be announced. In 1959 the "super-ridings" were broken up and the voting system was made standard across the province.