Right, I did some poking around, and found out some information about how long it’s taken for changeovers in Canadian governments at the federal level.
Hope this answers your question, The Ryan. By my calculations, the average time for a transition in Canadian federal politics, not counting the anomalous episode with PM Mackenzie in 1873, is 15.3 days.
In the following table, I’ve set out the election date, and then the date that the new Prime Minister and Cabinet were sworn in, followed by the elapsed time.
Note that I’ve only included the cases where a Prime Minister has lost the election, and been replaced by a new Prime Minister. I’ve not included the cases where a PM has retired and a new PM has been selected by the party without a general election - it’s only the “hostile takeovers,” so to speak.
For example, PM Pearson, a Liberal, resigned in 1968. The Liberals then chose Pierre Trudeau as their party leader, so he became PM without an immediate general election. (Of course, he called one soon afterwards, to gain his mandate to govern, and won a landslide.) Similarly, Campbell isn’t shown taking over from Mulroney in 1993. (Of course, she called an election soon afterwards to gain her mandate to govern, and led the PCs to the worst defeat in Canadian history - they went from having a majority to having 2 seats, total - Campbell lost her own seat.)
Since I’m only giving the dates for the hostile takeovers, several PMs aren’t included in the table.
There are also a couple of anomalies: Prime Minister Mackenzie in 1873, and Prime Minister Meighen in 1926. I explain those in notes at the end.
**New PM Election Day Sworn In Time Elapsed**
Mackenzie January 22, 1874* November 7, 1873 2 months, 15 days
Macdonald September 17, 1878 October 17, 1878 1 month
Laurier June 23, 1896 July 11, 1896 18 days
Borden September 21, 1911 October 10, 1911 19 days
King December 6, 1921 December 29, 1921 23 days
Meighen June 8, 1926** June 29, 1926 21 days
King September 14, 1926 September 25, 1926 11 days
Bennett July 28, 1930 August 7, 1930 10 days
King October 14, 1935 October 23, 1935 9 days
Diefenbaker June 10, 1957 June 21, 1957 11 days
Pearson April 8, 1963 April 22, 1963 14 days
Clark May 22, 1979 June 4, 1979 13 days
Trudeau February 18, 1980 March 3, 1980 13 days
Mulroney September 4, 1984 September 17, 1984 13 days
Chrétien October 25, 1993 November 4, 1993 10 days
**Average 15.3 days**
- Alexander Mackenzie became Prime Minister before he won the election. What happened was that the Conservatives under Sir John A. Macdonald got caught in an ugly scandal, and lost a vote of confidence in Commons. Party discipline was weaker at that time, and the Governor General asked Mackenzie, the Leader of the Opposition, to form a government. Mackenzie took office and won the confidence of the House, and then called the elections two months later.
** Arthur Meighen became PM as a result of a similar episode. PM King’s government was in danger of losing a vote of censure in the House. King asked the GovGen for a dissolution and elections, but the GovGen refused, saying that he did not want to interfere with the House while a major item like a vote of censure was pending. King resigned in a huff, leaving Her Majesty without a government for three weeks. The GovGen called on Meighen, who eventually was able to form a government, without going to the polls. (He in turn lost the confidence of the House and then there was an election, which King won.) I’ve used the date of King’s resignation as the equivalent to the election date for the data on Meighen.