RALEIGH, N.C. (WNCN) — Thanksgiving is less than two weeks away, and millions of Americans will head to the grocery stores to prepare for the feast.

Thanksgiving is always on a Thursday — but why?

The answer goes back to 1621, which was when the first Thanksgiving was celebrated. According to the Old Farmer’s Almanac, the Pilgrims’ first Thanksgiving took place in mid-October instead of November.

The Almanac states that beginning in 1668, November 25 was the “legal” day of Thanksgiving, but that only lasted for five years.

Thursday may have been a tradition to distance the holiday from the Sabbath day among the Puritan colonists. The Almanac states that Thursday was also a lecture day in New England and ministers would give a sermon every Thursday afternoon.

Since George Washington was president, Thursday was always the observed Thanksgiving day and Abraham Lincoln proclaimed the national day of Thanksgiving to be the last Thursday of November in 1863, according to the Almanac. The proclamation was later amended to the fourth Thursday in November.

Once Thanksgiving passes, retailers can officially begin the holiday shopping season.