Determination of the day of the week possible to do all the calculations in one's head with a little practice). None of the methods given here perform range checks, so unreasonable dates will produce erroneous results. Every seventh day in a month has the same name as the previous: "Corresponding months" are those months within the calendar year that start on the same day of the week. For example, September and December correspond, because September 1 falls on the same day as December 1. Months can only correspond if the number of days between their first days is divisible by 7, or in other words, if their
Labor Day By the time it became an official federal holiday in 1894, thirty U.S. states officially celebrated Labor Day. All U.S. states, the District of Columbia, and the United States territories have subsequently made Labor Day a statutory holiday. The date of May 1 (an ancient European folk holiday known as May Day) emerged in 1886 as an alternative holiday for the celebration of labor, later becoming known as International Workers' Day. The date had its origins at the 1885 convention of the American Federation of Labor, which passed a resolution calling for adoption of the eight-hour day effective May 1,