Note — After sharing an earlier version of this post with my friend JJ McCullough, he noted that many historical sources on Canadian election data differ considerably: you need to be careful about what sources you pull from. He has produced a wonderful website on Canada (The Canada Guide), which also covers historical elections. You should check it out!
Mergers and acquisitions
The creation of new parties and the mergers of old ones is a perfectly normal part of the Parliamentary system and one that is sometimes overlooked: in discussions on electoral reform, it's tempting to focus on which party today would benefit from a proposed change (after a quick Google, here is an example). Although these articles can be fun speculation, there is a problem with this sort of analysis: it assumes today's political parties will remain static even after some fundamental change to the voting system.
Over the course of two short posts, I want to show you a longer time series of Canadian elections and a couple quick cuts of the data to show how parties rise and fall. Their emergence (and destruction) is a crucial part of the "first past the post" (FPTP) system — in fact, a crucial part of any democratic political system! Ideological (or other) movements must iron out their difference and coalesce into a well-organized party so as to present the country with a coherent and unified option for Government. These "broad churches" are themselves smaller deliberative bodies, where different factions must compromise.
When factions cannot find reasonable compromise within an existing party, they can start their own. This is what happened when Lucien Bouchard left the PCs to form the Bloc Quebecois or when Preston Manning (and others) founded Reform. The converse is also true: Stephen Harper and Peter MacKay merged the Canadian Alliance and the Progressive Conservatives, which created the Conservative Party in 2003.
Even over the last decade there has been plenty of speculation on whether the Liberals and NDP should merge (here is but one example).
Federal votes and election outcomes
I've pulled the historical Federal election outcomes since Confederation from a variety of sources (although mainly from the Library of Parliament). Below are two plots: the top one shows the distribution of seats from every election since 1867, while the lower one shows the popular vote percentages.
I have ordered the parties (roughly) so that the Conservative / Right-wing parties are near the top of the chart and the Liberals are at the bottom. Since these are the only two parties that have held government, this should show the back-and-forth between them over time (in particular, whenever one crosses the white 50% line).