[1] York—Simcoe is a rural constituency based in the York Region and Simcoe County, just to the north of the Greater Toronto Area.

York—Simcoe has been considered a safe seat for the Conservatives, but at the 2015 election the Liberal Party saw a huge increase in share of vote; 26 percentage points.

[3] Scot Davidson, Heather Fullerton, and Jason Verkaik sought the Conservative nomination.

[8] Sébastien Corriveau, leader of the Rhinoceros Party, stated his intention to run in this by-election,[9] but he did not register.

[10] The Speaker's warrant regarding the vacancy was received on October 1, 2018; under the Parliament of Canada Act the writ for a by-election had to be dropped no later than March 30, 2019, 180 days after the Chief Electoral Officer was officially notified of the vacancy via a warrant issued by the Speaker.