Presidential Thanksgiving proclamations and speeches have been popular throughout American history. Within the federal government, the tradition pre-dates the U.S. Constitution adopted in 1789, and was observed by the Continental Congress.
President George Washington issued the first presidential Thanksgiving proclamation but that was not officially observed as a concurrent tradition by every president until Abraham Lincoln proclaimed a national day of Thanksgiving to be observed on Thursday, November 26, 1863.
Before Lincoln, Thanksgiving was generally promoted in government at the state level.
President Franklin Delano Roosevelt officially made the holiday the fourth Thursday in November in 1942.