*Labor Day is held the first Monday of September. In 2012, that’s September 3.
President Grover Cleveland made Labor Day an official United States holiday all the way back in 1894. At the time, Cleveland hoped that it would smooth over the conflicts between labor unions and employers. Some 30 people had been killed that summer during the Pullman Strike. To get an idea of the situation (albeit a fun, musical, and Disney-ified idea), you could watch the Newsies, based on the New York City newsboys strike in 1899.
Tradition states that you should celebrate Labor Day by attending parades while wearing white clothes and/or seersucker (before you pack them away tomorrow). Of course, modern celebrations seem to center more around the mall and labor day sales.
You could also party with an eye towards the other two holidays on this September 3: National Skyscraper Day and US Bowling League Day!
“Be at rest once more, O my soul,
for the Lord has been good to you.”