When was the First Thanksgiving?

Abigail Addison 

Thanksgiving Day did not become an official holiday until Northerners dominated the federal government. While there was some  tensions  in the mid-19th century, the editor of the popular magazine Godey’s Lady’s Book, Sarah Josepha Hale, campaigned for a national Thanksgiving Day to promote unity. She finally won the support of President Abraham Lincoln. On October 3, 1863, during the Civil War, Lincoln proclaimed a national day of thanksgiving to be celebrated on Thursday, November 26. 

The holiday was annually proclaimed by every president after that, and the date chosen, with few exceptions, was the last Thursday in November. President Franklin D. Roosevelt, however, attempted to extend the Christmas shopping season, which usually begins with the Thanksgiving holiday, and to boost the economy by moving the date back a week, to the third week in November. But not all states agreed, and, after a joint resolution of Congress in 1941, Roosevelt proclaimed the fourth Thursday in November (which is not always the last Thursday) as Thanksgiving Day in 1942.

Whatever you do for Thanksgiving, enjoy yourself, and be safe if you go out shopping!

I got my information from Thanksgiving Day | Meaning, History, & Facts | Britannica