Labor Day is a holiday that was first celebrated in 1882. It began as a demonstration by a union group to focus on the needs of laborers. What began as a single movement in NYC that September day in 1882, drew the attention of other states and by 1894 28 states had passed legislation to create a Labor Day holiday. That same year, Congress enacted a law making the first Monday in September as Labor Day. This legal holiday is still celebrated today.
Labor Day is still seen as a day to celebrate the workers, although there are very few labor demonstrations or union -organized protests on Labor Day. It is also seen as a holiday that celebrates the end of summer (while Memorial Day welcomes summer).
Although we celebrate the holiday as Labor Day in the US, other countries call it May Day.