Sometimes called the "unofficial end of summer," Labor Day is a legal holiday created in 1894 by 28 Stat. 96 and is observed on the first Monday of September. Following the growth of the labor movement, Senator James Henderson Kyle of South Dakota introduced S. 730 to the 53rd Congress to make Labor Day a legal holiday. (Source: Department of Labor )
In a report (H. Rept. 902) to accompany H.R. 28, 53rd Congress, the House Committee on Labor stated the celebration of Labor Day as a national holiday would “tend to increase the feeling of common brotherhood among men in all crafts and callings, and at the same time kindle an honorable desire in each craft to surpass the rest.” At the time, 23 states had already recognized Labor Day as a legal holiday. (Source: Senate.gov (PDF) )
Did you know that many Federal holidays fall on a Monday because of the 1968 Uniform Monday Holiday Act?
82 Stat. 250 - An Act to provide for uniform annual observances of certain legal public holidays on Mondays, and for other purposes
The U.S. Code states that the flag should be displayed "especially on...Labor Day, first Monday in September."
4 U.S.C. 6 - Time and occasions for display contained within Title 4 - Flag and Seal, Seat of Government, and the States Chapter 1 - The Flag, laws in effect as of January 3, 2016