On the 1st of May, many countries all over the world, celebrates the Labor Day, an annual holiday to celebrate the economic and social achievements of workers. Its origin dates back to a demonstration organized by the Knights of Labor (an American labor organization established in 1869) in New York on the 5th of September 1882. In 1884 a resolution was approved so that the event could be celebrated yearly and the 1st of May was suggested as the date of this holiday.
After the tragic events of the Haymarket affair (May 1886) in Chicago, this date was definitely set. On the 4th of May 1886 the workers gathered in Chicago, near the McCormick factory which produced farm machinery. It was supposed to be a peaceful rally in support of workers striking for an eight-hour day. An unknown person threw a dynamite bomb at police as they acted to disperse the public meeting. The police reacted and killed seven police officers and at least four civilians; scores of others were wounded. The then-president, Grover Cleveland, considered the Labor Day as a chance to commemorate these episodes.
In Europe this holiday was made official by socialist delegates of the Second International met in Paris in 1889. In Italy the biggest event to celebrate the Labor Day, is the “May 1st concert” organized since 1990 in Rome by the trade union associations CISL ( Italian Confederation of Trade Unions), CGIL (Italian General Confederation of Labor) and UIL (Italian Labor Union).