The Separatists, who had initially fled to the Netherlands to escape religious persecution in England in 1607, were the founders of Plymouth Colony in 1620. After residing in Amsterdam and Leiden, the leaders feared their children were being influenced by Dutch customs and opted for the "New World."
The Separatists obtained a patent from the London Virginia Company and set sail from Plymouth, England aboard the Mayflower and the Speedwell. Speedwell turned out to be unseaworthy and the Mayflower made the Atlantic voyage alone. The voyage took just over two months, with the ship landing near Cape Cod on 9 November 1620. [They had planned on landing at the mouth of the North [Hudson] River.]
Before landing, the men on board the ship agreed to the Mayflower Compact, the social contract by which they would live. The settlers, who became known as the Pilgrims, faces a severe first winter and only survived with the help of Squanto and chief Massasoit's people. The autumn celebration in 1621 gave birth to our Thanksgiving holiday.
The Fortune arrived in November 1621 with new settlers. Other ships would arrive over the next few years bringing more colonists.
Plymouth [capital], Barnstable, Eastham, Taunton, Bristol, Barnstable and other towns were built in the colony. The colony was divided into Bristol, Plymouth and Barnstable counties.
Plymouth Colony merged with Massachusetts Bay Colony in 1691.
Pilgrim William Brewster, son Jonathan, and Gov. Thomas Prence were among my Plymouth ancestors.
More at: https://en.wikipedia.org/wiki/Plymouth_Colony