As it turns out, this piece of Thanksgiving history dates all the way back to Franklin D. Roosevelt. While Abraham Lincoln gave the holiday a semi-defined date when he declared the last Thursday in November to be the official date of Thanksgiving observation during his 1863 proclamation, things became complicated when, in both 1933 and 1939, November ended up having not four weeks, but five.ae0fcc31ae342fd3a1346ebb1f342fcb What could possibly be the problem with moving Thanksgiving back a week every few years? Well, as the Library of Congress explains, business owners feared that the further Thanksgiving was pushed, the less time (and therefore money) people would spend doing their Christmas shopping. RELATED: For more up-to-date information, sign up for our daily newsletter. In a letter addressed to FDR postmarked Oct. 2, 1933, the Downtown Association of Los Angeles expressed these concerns. “Thanksgiving, this year, according to the usual custom, would fall upon November 30th, the last Thursday in November, which would leave but twenty shopping days before Christmas,” they noted. “It is an established fact that Christmas buying begins vigorously every year in the retail stores the day following Thanksgiving and that the Thanksgiving to Christmas period is the busiest retail period of the whole year.” It appears that Roosevelt took the concerns of his constituents seriously. In 1939, the president issued a proclamation moving the holiday to the second-to-last Thursday in November. Several states refused to acknowledge this change, though, and so in 1941, the Senate moved to officially establish the holiday on the fourth Thursday of the month. Obviously this doesn’t solve the Christmas shopping problem every year: This year, for example, Thanksgiving falls on the late date of Nov. 26. The Senate resolution was signed into law by Roosevelt on Dec. 26, 1941, and the fourth Thursday in November has been the day we celebrate Thanksgiving ever since! And for more fun facts about Turkey Day, here are 30 Thanksgiving Facts to Share With Your Family.