Mount Vernon Optic-Herald

Thanksgiving Day is a holiday celebrated primarily in the United States and Canada. Thanksgiving is celebrated each year on the second Monday of October in Canada and on the fourth Thursday of November in the United States. 

In the United States, the modern Thanksgiving holiday tradition is commonly traced to a 1621 celebration at Plymouth in present-day Massachusetts. The 1621 Plymouth feast and thanksgiving was prompted by a good harvest.  As President of the United States, George Washington proclaimed the first nation-wide thanksgiving celebration in America marking November 26, 1789, "as a day of public thanksgiving and prayer to be observed by acknowledging with grateful hearts the many and signal favours of Almighty God"

Thanksgiving in the United States was observed on various dates throughout history. From the time of the Founding Fathers until the time of Lincoln, the date Thanksgiving was observed varied from state to state. The final Thursday in November had become the customary date in most U.S. states by the beginning of the 19th century. Thanksgiving was first celebrated on the same date by all states in 1863 by a presidential proclamation of Abraham Lincoln. Influenced by the campaigning of author Sarah Josepha Hale, who wrote letters to politicians for around 40 years trying to make it an official holiday, Lincoln proclaimed the date to be the final Thursday in November in an attempt to foster a sense of American unity between the Northern and Southern states.[23] Because of the ongoing Civil War and the Confederate States of America's refusal to recognize Lincoln's authority, the concept of "nationwide" Thanksgiving did not totally take effect until Reconstruction was completed in the 1870s.

It was not until December 26, 1941, that the unified date changed to the fourth Thursday (and not always final) in November—this time by federal legislation. President Franklin D. Roosevelt, after two years earlier offering his own proclamation to move the date earlier, with the reason of giving the country an economic boost, agreed to sign a bill into law with Congress, making Thanksgiving a national holiday on the fourth Thursday in November.