May Day Is Born News of the tragedy sent shockwaves through the labor movement worldwide. In 1889, socialists declared May 1 International Workers Day - or May Day - to commemorate the Haymarket martyrs and build international workers' solidarity. Today, May Day is celebrated in over 80 countries, with mass rallies and a day off from work. But the holiday that was born in Chicago is not officially celebrated in the U.S. In 1894, Congress declared Labor Day a federal holiday, to be observed the first Monday in September. Although there was pressure to set the holiday on May 1, President Grover Cleveland - who wanted to distinguish Labor Day from Chicago's workers' uprising - refused. In the 1930s, many U.S. unions organized May Day celebrations, with millions of workers marching in parades in New York and other cities. In 2006, hundreds of thousands immigrant workers marked the holiday with protests against an anti-immigration bill. May Day, the international symbol of labor solidarity, lives!