May Day is a celebration of the international labour movement. May 1 is a national holiday in more than 80 countries and celebrated unofficially in many other countries.
On May 1, 1886, Chicago unionists, reformers, socialists, anarchists, and ordinary workers combined to make the city the center of the national movement for an eight-hour day. Between April 25 and May 4, workers attended scores of meetings and paraded through the streets at least 19 times. On Saturday, May 1, 35,000 workers walked off their jobs. Tens of thousands more, both skilled and unskilled, joined them on May 3 and 4. Crowds traveled from workplace to workplace urging fellow workers to strike. Many now adopted the radical demand of eight hours' work for ten hours' pay. Police clashed with strikers at least a dozen times, three with shootings. (Read more: Encyclopedia of Chicago )
Still in our days the importance and the unity of this day remains the same. The posters below show these elements that make up the meaning of the day.