International Workers' Day

International Workers' Day, also known as Labour Day in some places, is a celebration of laborers and the working classes that is promoted by the international labor movement, Anarchists, Socialists, and Communists and occurs every year on May Day, May 1, an ancient European spring holiday.^[1][2] May 1 was chosen as the date for International Workers' Day by the Socialists and Communists of the Second International to commemorate the Haymarket affair in Chicago that occurred on May 4, 1886.^[2]

Being a traditional European spring celebration, May Day is a national public holiday in many countries, but in only some of those countries is it celebrated specifically as "Labour Day" or "International Workers' Day". Some countries celebrate a Labour Day on other dates significant to them, such as the United States which celebrates Labor Day on the first Monday of September.