This is a list of electoral districts or ridings in Canada for the Canadian federal elections of 1917 and 1921.
Electoral districts are constituencies that elect members of Parliament in Canada's House of Commons.
When the new arrangement was devised in 1914, it gave PEI only three seats. After public complaints, a rule that a province could not have fewer MPs than Senators was introduced giving PEI back a fourth seat in 1915. The arrangement with only three PEI seats was never used in an election.