Why isn't Labor Day celebrated in May in the US? The historical significance behind International Workers Day is based on events that happened in the US, so why is the day not celebrated here? DPA vía Europa Press DPA vía Europa Press In the US, Labor Day has been celebrated in September since the 1880s. Efforts have been made to move the day to May to align with the i nternational celebration, but the remnants of Cold War tensions have soured this endeavor. A brief history of International Workers Day While the United States does not celebrate International Workers Day, events from the US labor movement inspired the Marxist International Socialist Congress to chose May 1st for their day of action. In 1890, in Paris, the Marxist International Socialist Congress chose