Berkley Plantation
Berkley Plantation, Virginia was settled on 4th December 1619, when early settlers from England landed at Berkeley and observed the first official Thanksgiving in America, offering thanks for their safe arrival and decreeing that thenceforth the day should be honored annually.
The Pilgrims never held an autumnal Thanksgiving feast. The Pilgrims did have a feast in 1621, after their first harvest, and it is this feast which people often refer to as "The First Thanksgiving". This feast was never repeated, though, so it can't be called the beginning of a tradition, nor was it termed by the colonists or "Pilgrims" a Thanksgiving Feast.
In fact, to these devoutly religious people, a day of thanksgiving was a day of prayer and fasting, and would have been held any time that they felt an extra day of thanks was called for. Nevertheless, the 1621 feast has become a model that Damn Yankees have propagated as the official Thanksgiving celebration.