For 36 years, magazine editor Sarah Josepha Hale wrote to four sitting Presidents trying to make Thanksgiving a national holiday. In September 1863, the fifth one finally said yes.
Hale was 74 years old when she sent the letter that changed the calendar. She was also the most influential woman in American magazine publishing. As editor of Godey’s Lady’s Book in Philadelphia, the largest-circulation women’s magazine in the country, she had been campaigning for a unified national Thanksgiving Day since 1827. She also happened to be the author of “Mary Had a Little Lamb,” which she had written in 1830. Zachary Taylor declined her Thanksgiving appeal. Millard Fillmore declined. Franklin Pierce declined. James Buchanan declined. Then Abraham Lincoln took the letter.
Hale’s letter to Lincoln is dated September 28, 1863. She asked him to make “the day of our annual Thanksgiving made a National and fixed Union Festival.” A digitized version is below, and click here to read the transcribed text.

Lincoln issued the proclamation five days later, on October 3, 1863. Secretary of State William Seward did the actual drafting, and Lincoln signed it. The timing matters. Gettysburg had been fought just three months earlier, and the “civil strife” line in the proclamation is not abstract. The Union had buried thousands of its dead in Pennsylvania that July, and the country needed something to gather around.
I do therefore invite my fellow citizens in every part of the United States, and also those who are at sea and those who are sojourning in foreign lands, to set apart and observe the last Thursday of November next, as a day of Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens.
Read the entire proclamation here.

Every president since Lincoln has issued an annual Thanksgiving Proclamation. The unbroken thread runs straight back to Hale’s letter. Franklin Roosevelt briefly tried to shift the date forward by a week in 1939 to extend the Christmas shopping season, a move dubbed “Franksgiving” by its critics, and 23 states refused to go along with him. The mess sparked enough backlash that Congress legislated the holiday permanently to the fourth Thursday in November in 1941. That settled the one piece of the calendar Lincoln himself had not pinned down.
Sarah Josepha Hale lived to see her work survive. She died in 1879 at age 90, having spent more than half her adult life on a single campaign. If you have ever eaten turkey on the last Thursday of November, she is part of why.
For more on the man who signed her victory into national habit, see this colorized 1865 portrait of Abraham Lincoln, taken by Alexander Gardner at his 7th Street studio two months before the assassination.