The Winnipeg General Strike of 1919 was one of the largest strikes in Canadian history. For six weeks, May 15 to June 26, more than 30,000 strikers brought economic activity to a standstill in Winnipeg, Manitoba, which at the time was Canada's third largest city.

In the short term, the strike ended in arrests and bloodshed. Over time it contributed to the development of a stronger labour movement and the tradition of social democratic politics in Canada. Winnipeg itself would see decline over the remainder of the twentieth century as both the east and west coasts had less need of its transport networks.

There were many background causes for the strike, most of them related to the prevailing social inequalities and the impoverished condition of the city's working class. Wages were low, prices were rising, employment was unstable, immigrants faced discrimination, housing and health conditions were poor. In addition, there was resentment of the enormous profits enjoyed by employers during the war. Soldiers returning from the war were determined to see improved social conditions and opportunities after their harrowing experiences overseas. Most workers did not have union representation, but many were influenced by the hope of achieving greater economic security through unions.

Many workers were also influenced by socialist ideas voiced by local reformers, radicals and revolutionaries. These attracted greater interest, especially among the large population of immigrants from Eastern Europe, after the Russian Revolution of 1917. A meeting of western labour delegates in Calgary in March 1919 adopted numerous radical resolutions, including support for a five-day week and a six-hour day. They also called for the establishment of a new union centre, the One Big Union, to promote class solidarity by uniting workers from all trades and industries in one organization. The idea that the OBU instigated the general strike is misleading, as the OBU was not formed until June 1919. However, the "one big union" idea contributed to the atmosphere of unrest. Similar volatile conditions existed elsewhere in Canada, and in other countries around the world, at the end of World War I, but the combination of circumstances in Winnipeg proved to be explosive.

The most immediate cause of the strike involved support for collective bargaining in the metal trades and building trades, where workers were attempting to negotiate contracts through their trades councils. When the Metal Trades Council and the Building Trades Council had both failed to secure contracts with employers by the end of April, they went on strike, the building trades on May 1 and the metal trades on May 2. Shortly afterwards, the situation was discussed at meetings of the Winnipeg Trades and Labour Council, the umbrella body for the city's unions. The Labour Council decided to call on their 12,000 affiliated members to vote on a proposal for a general strike. On a smaller scale, this tactic had achieved success for striking city workers a year earlier in 1918. Preliminary results of the vote among the Labour Council's member unions were announced on May 13. The outcome showed overwhelming support for a general strike, 8,667 to 645. Ernest Robinson, secretary of the Labour Council, issued a statement that "every organization but one has voted in favour of the general strike" and that "all public utilities will be tied-up in order to enforce the principle of collective bargaining". A Strike Committee was established, with delegates elected by the city's unions. The leadership included both moderate trade unionists, such as James Winning, a bricklayer who was president of the Trades and Labour Council, and socialists such as R. B. Russell, a machinist who favoured the OBU.

At 11 am on Thursday, May 15, 1919, virtually the entire working population of Winnipeg went on strike. Around 30,000 workers in the public and private sectors walked off their jobs, and the city experienced a sudden cessation of many activities. The Strike Committee requested the police force, who had voted in favour of the strike, to remain on duty. Workers at the city waterworks also remained on the job to provide service at reduced pressure. Union membership had increased substantially during the spring of 1919, but most of the people who came out in support of the general strike were not union members. For instance, the first to leave work, at 7:00 a.m., were the telephone operators, the "hello girls" at the city telephone exchanges, who were not at this time union members. Also on the first day of the strike, the major organizations of returned soldiers announced their support and were active throughout the six weeks of the strike.

In the early days of the strike, according to historian David Bercuson, "The atmosphere was almost festive, the belief in ultimate victory strong." Participants assembled in city parks to listen to speakers report on the progress of the strike and discuss the many related social reform issues of the time. To ensure that strikers were kept informed of developments, the Strike Committee also published a daily Strike Bulletin. This newspaper urged the strikers to remain peaceable: "The only thing the workers have to do to win this strike is to do nothing. Just eat, sleep, play, love, laugh, and look at the sun ... Our fight consists of doing no fighting."

Women leaders played an important part in the strike. They encouraged female workers to go on strike, encouraged strikers in their strike efforts and built solidarity among strikers. Helen "Ma" Armstrong was one of two women on the Strike Committee. She encouraged young working women to join the strike and often spoke on street corners and at public meetings and was arrested multiple times. The Women's Labour League raised money to help women workers pay rent. Women also set up a kitchen where hundreds of meals were served every day. On June 12 a "ladies day" was held at Victoria Park, where women occupied seats of honour to hear a speech by J.S. Woodsworth promoting the emancipation of women and need for equality of the genders.