Thanksgiving is a national holiday in the United States observed on differing dates. From the time of the Founding Fathers until Abraham Lincoln made it a national holiday in 1863, the date of observance varied from state to state. Abraham Lincoln set national Thanksgiving by proclamation for the final Thursday in November in celebration of the bounties that had continued to fall on the Union and for the military successes in the war. On October 31, 1939, President Franklin D. Roosevelt signed a presidential proclamation changing the holiday to the next to last Thursday in November in an effort to boost the economy. The earlier date created an extra seven days for Christmas shopping since at that time retailers never began promoting the Christmas season until after Thanksgiving.
Personally I call Thanksgiving a speed bump between Halloween and Christmas.