"[3] The CUPW currently has approximately 55,000 members[4] and has a long, vibrant history originating in 1965 when the union was formed out of the Canadian Postal Employees Association (CPEA).

[clarification needed] A 1978 strike resulted in CUPW president Jean-Claude Parrot being jailed when the union defied back-to-work legislation passed by the Canadian parliament.

In 1981, after another strike, CUPW became the first federal civil service union in Canada to win the right to maternity leave for its members.

[citation needed] In 1981, Canada Post was transformed from a government department to a crown corporation, fulfilling a long-standing demand by the union.

[citation needed] In 2003, CUPW successfully completed the organizing of approximately 6,000 Rural and Suburban Mail Carriers (RSMC) into the Union and won a first collective agreement for these workers.

[citation needed] Failing to reach a new agreement, the union initiated a series of rotating strikes across the country on October 22, 2018.

On August 28, 2024, CUPW have posted on their website that their National Executive Board have scheduled strike votes meetings from September 9, 2024, to October 20, 2024.

Following a request by Labour Minister Steven MacKinnon on December 12th, 2024, the Canada Industrial Relations Board ordered strikers to return to work by the morning of the 17th, ending the strike.

It spends funds in participating on issues such as child care, Cuba, abortion, Colombia, anti-racism, anti–North American Free Trade Agreement (NAFTA), anti–global capitalism, marijuana decriminalization, campaigns for women's equality and human rights.