I came across a posting of a 2000 essay by Rabbi Elias Lieberman, suggesting a connection between the New England Thanksgiving celebrations and the ancient Jewish festival of Sukkot, known to us as the “feast of tabernacles” (or “festival of booths”) or the “feast of ingathering”.

Sukkot is mentioned in the Old Testament books of Exodus, Leviticus, and Deuteronomy; From Leviticus 23:

On the fifteenth day of the seventh month, when you have gathered in the produce of the land, you shall celebrate the feast of the Lord seven days. On the first day shall be a solemn rest, and on the eighth day shall be a solemn rest. And you shall take on the first day the fruit of splendid trees, branches of palm trees and boughs of leafy trees and willows of the brook, and you shall rejoice before the Lord your God seven days. You shall celebrate it as a feast to the Lord for seven days in the year. It is a statute forever throughout your generations; you shall celebrate it in the seventh month. You shall dwell in booths for seven days. All native Israelites shall dwell in booths, that your generations may know that I made the people of Israel dwell in booths when I brought them out of the land of Egypt: I am the Lord your God.”

Our early Pilgrims, known as The Separatists, were a persecuted Calvinist sect who left England and sojourned in Holland for a time. Predominantly they settled in the university city of Leiden, where they produced cloth for the textile industry. They would have rubbed shoulders with another persecuted minority group, the Sephardic Jews, who had fled from persecution in Roman Catholic Spain.

In his 1996 book The World of Jewish Cooking, Rabbi Gil Marks notes:

Before reaching Plymouth Rock, the Pilgrims spent several years in Holland, where they came into contact with Sephardim who had immigrated to that country, following the expulsion from Spain.

He points out that a classic Pilgrim dish, Boston baked beans, are a variation of a slow baked sabbath bean stew known as “Shkanah”.

As Rabbi Lieberman puts it:
While we cannot be certain about what motivated those Pilgrim settlers to initiate a feast of thanksgiving, it is likely that they consciously drew on a model well-known to them from the Bible they cherished. Seeing themselves as new Israelites in a new “promised land,” the Pilgrims surely found inspiration in the Bible, in the Books of Leviticus and Deuteronomy, in which God commands the ancient Israelites to observe the Feast of Booths — in Hebrew, Sukkot, “to rejoice before Adonai your God” at the time of the fall harvest [Lev. 23:40].
(Available at interfaithfamily.com)

There exists debate as to how much the early Pilgrims were influenced by Jewish practices. As quoted in Jewish News Service, Brandeis University professor of American Jewish History, Jonathon Sarna says,

The Puritans did not believe in fixed holidays. If it was a good season, they would announce a thanksgiving, but it’s not like the Jewish holiday which occurs on the 15th of the month of Tishrei (Sukkot). They did not believe in that. So in that respect it’s different.”

Regardless, we offer our warmest greetings to all who celebrate Thanksgiving tomorrow. It is customary at Sukkot, to sing Psalm 136:1-3, and we here take up the refrain as well:

O give thanks unto the Lord; for he is good: for his mercy endureth for ever.
O give thanks unto the God of gods: for his mercy endureth for ever.
O give thanks to the Lord of lords: for his mercy endureth for ever.