Photo: The Canadian Press

A mail-in voting package that voters will receive if requested is seen in Calgary, Alta., Thursday, Sept. 2, 2021. THE CANADIAN PRESS/Jeff McIntosh

People voting by mail could play a crucial role in deciding the outcome of the Sept. 20 federal election.

Postal votes could dictate which party wins in a series of closely fought ridings where just a handful of votes could decide the outcome.

Among them is Coquitlam—Port Coquitlam in British Columbia — Canada's tightest race in the 2019 election — where the Liberals fought off a Conservative challenge by only 153 votes.

By today's deadline, more than 5,000 residents in that riding had applied to vote by mail.

Election officials begin counting local postal votes the morning after election day, raising the prospect of a delayed result and nail-biting finish.

About 914,000 electors across Canada had applied for mail-in ballots by today's deadline and more than 500,000 had returned them.