May Day | History, Meaning, Traditions, & Facts
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May Day, day that commemorates the historic struggles and gains made by workers and the labour movement. It is observed on May 1 in many countries, where it is the occasion for demonstrations and rallies in support of workers. It was of particular significance in the Soviet Union during the 20th century.

In 1889 an international federation of socialist groups and trade unions designated May 1 as a day in support of workers, in commemoration of the Haymarket Riot in Chicago (1886). Five years later, U.S. Pres. Grover Cleveland, uneasy with the socialist origins of Workers’ Day, signed legislation to make Labor Day—already held in some states on the first Monday of September—the official U.S. holiday in honour of workers. Canada followed suit not long afterward.