According to The Department of Labor:
“Labor Day, the first Monday in September, is a creation of the labor movement and is dedicated to the social and economic achievements of American workers. It constitutes a yearly national tribute to the contributions workers have made to the strength, prosperity, and well-being of our country.”
The first Labor Day holiday was celebrated on Tuesday, September 5, 1882 in New York City. The first Monday in September was chosen as the official holiday in 1884. 23 states adopted the holiday by 1894. On June 28, 1894, Congress passed an act making it a legal holiday in District of Columbia and the territories.