Thanksgiving was made a national holiday by President Abraham Lincoln in 1863, even in the midst of dealing with a nation torn by civil war. On Oct. 3, 1863, he issued a proclamation calling for a time of "thanksgiving and praise" to be celebrated on the last Thursday of November.
Thanksgiving had been celebrated sporadically during the early history of the United States, with President Washington calling for a national day of thanksgiving in 1789. It did not, however, become an annual celebration until President Lincoln's proclamation. From 1863 until 1939, the last Thursday of November was set aside as Thanksgiving. President Franklin Roosevelt tweaked the date in 1939, changing it from the last to the fourth Thursday in November in an effort to give more shopping days between Thanksgiving and Christmas.