Every year when October ends and November begins, the countdown to Thanksgiving (and the food that comes with it) officially starts. Even if you never have that year's exact date memorized, you can easily figure out when the feast will take place because it always falls on the fourth Thursday in November. This is a great rule of thumb to know, but do you know why it's the case? It wasn't always like this, according to the Library of Congress, and there's some interesting history behind the Thanksgiving date.
Let's look back all the way to 1863 when Abraham Lincoln was president and Thanksgiving was proclaimed to be celebrated on the last Thursday of November nationwide. A couple years later in 1865 President Andrew Johnson announced the first Thursday of the month as the official Thanksgiving Day. Then in 1869 President Ulysses S. Grant declared the third Thursday in November as the holiday.
In all of those intermediary years, the holiday was celebrated on the last Thursday of November as President Lincoln had said. It wasn't until until 1939 under President Franklin D. Roosevelt's term that the penultimate Thursday in November would be henceforth known as Thanksgiving Day. This decision was made following pressure from National Retail Dry Goods Association, as they wanted the holiday shopping season to be a little bit longer so customers would have more time to buy.
This proclamation in 1939 initially only referred to those in Washington, D.C. and federal employees. Although governors typically follow the president's proclamations on such decisions, only 23 of the 48 states at the time followed this date. Twenty three states celebrated on Nov. 30, the last Thursday of the month that year, and Colorado and Texas observed Thanksgiving on both of the dates.
The next couple of years there was still some vague confusion about which Thursday of the month was officially Thanksgiving, so President Roosevelt eventually signed legislation that declared the fourth Thursday in November as the holiday. The legislation also meant that future presidents could not change the date again. This way, because of how the calendar works, sometimes Thanksgiving happens to be the last Thursday of November—which, if you were wondering, is the case this year.