Embedded Files
One of the interesting aspects of the Westminster parliamentary system that Canada uses is that the prime minister—the leader of the country—is just another parliamentarian, directly elected only by voters in their geographic district (in Canadian parlance, their riding).
I created a series of maps of each riding represented by Canada's prime ministers, 25 in all from Nova Scotia to Vancouver Island. 23 individuals have held the job since 1867; discrepancies arise from the fact that four PMs represented two or even three different ridings during their time in office, while another four never held a seat in the House of Commons (John Abbott, Mackenzie Bowell, Charles Tupper, and John Turner).
This was a technically challenging process as there is no comprehensive shapefile of historic ridings, so for those older than 1996 I had to reconstruct them based on the written boundary descriptions kept by the Library of Parliament.
These descriptions generally use existing subdivisions, for which shapefiles are available, as building blocks. They may also describe lines following those subdivisions' borders, or other features like roads and rivers. Here's a representative example:
Consisting of all those portions within the province of Saskatchewan of ranges twenty-two (22), west of the second meridian to seven (7), west of the third meridian, both inclusive, lying north of a line described as follows: Commencing at the southwest corner of township forty-four (44) in range seven (7) west of the third meridian; thence easterly along the south boundary of township forty-four (44) to the east boundary of range four (4) west of the third meridian; thence northerly along the east boundary of range four (4) to the southwest corner of the Duck Lake Indian Reserve, Nos. 96 and 97; thence easterly and northerly along the southern and eastern boundaries respectively of the said Duck Lake Indian Reserve to the south boundary of township forty-four (44) in range two (2), west of the third meridian; thence easterly along the south boundary of townships forty-four to the centre line of the South Saskatchewan river; thence downstream along the centre line of the South Saskatchewan river and the Saskatchewan river to its intersection with the eastern boundary of range twenty-two (22), west of the second meridian.
This description refers extensively to divisions of the Dominion Land Survey, which are denoted by township (row north of the 49th parallel) and range (column west of defined meridians).
It states that the riding comprises all of columns R22-W2 to R7-W3, north of a given line running from the southwestern corner of T44-R7-W3 to the intersection of the Saskatchewan River with the eastern edge of R22-W2.
I downloaded the DLS grid, extracted the townships and ranges indicated in the description, and drew the part of the southern boundary that runs through the river. I then dissolved everything to form the riding's shape, stretching all the way to the top of the province.
Some of the oldest descriptions could not be constructed from their constituent parts, as they were vague or used building blocks that no longer exist. For instance, here's Wilfrid Laurier's Quebec City riding:
Consisting of St. Roch's Ward and Jacques Cartier Ward, and that portion of the Banlieue to the North of a line prolonged towards the south-west from the southern extremity of Jacques Cartier Ward, along the Cime du Cap to the southwestern limit of the Banlieue.
The wards (quartiers) in question are long defunct as legal entities, and "the Banlieue" just means "the suburbs." Which suburbs? Apparently no further context was needed in 1860. In any event, it was impossible to precisely recreate borders like these using modern shapefiles.
Thankfully, I found a different invaluable resource for these cases: electoral atlases that have been scanned by Library and Archives Canada. By georeferencing these scans, I could digitize the boundaries by tracing over them.
Overall, this was a fun project that combined my interests in geography and political history. If you'd like a copy of the finished product, you can download a GeoJSON of all the ridings here.
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