Mrs. Hale frequently, almost incessantly, pushes for a very specific day for Thanksgiving to observed, the last Thursday in November. Almost all other harvest festivals happen sometime between August and October. Why is Thanksgiving in late November? The answer is simple, Mrs. Hale wanted a day that the entire country could keep all at once from the farthest south to the farthest north, without politics or any of life's normal distractions getting in the way.
“The last Thursday in November was suggested because then the agricultural labors of the year are generally completed; the elections are over; those autumnal diseases which usually prevail more or less at the South have ceased, and the summer wanders are gathered to their homes.”
Sarah Hale, Godey's Lady's Book 1863