The day honors the struggles and achievements of labor movements fighting for workers' rights. In some countries, it's a public holiday similar to Labor Day in the United States.

May Day rally draws thousands downtown in support of immigrants, workers: 'We need a united front' The crowd marched from Union Park to mark the global holiday for labor rights.

Is the United States the only country that celebrates May Day with protests? No. Countries across the globe mark May 1 as a day to celebrate labor and to highlight the problems workers face.