Before 1776, the British had concluded that the St. Lawrence Valley would remain French because the English-speaking colonists preferred to settle in the Thirteen Colonies. The American Revolution completely changed this situation. As of 1783, the Thirteen Colonies now formed a new country, the United States of America. Those who wanted to remain loyal to the king had to leave their home and village, and move to British territory. These people were the Loyalists.
Video narration available in French at http://primaire.recitus.qc.ca/sujets/9/groupes-sociaux/3733
As the Loyalists left the United States, they were harassed and hunted by their former neighbours, who had chosen to create a new country. They flocked in large numbers to the Province of Québec. So that they would not have to share a colony with the French-speaking Catholics of the St. Lawrence Valley, they obtained the creation of Upper Canada in 1791 when the Constitutional Act was passed.
However, some of them decided to live in Lower Canada anyway. They settled in the Upper Richelieu area and obtained the creation of a new zone that was not divided into seigneuries, but into townships, the Eastern Townships.
See also – Traces of the past: