Under the Proclamation, Quebec included the cities of Quebec and Montreal, as well as a zone surrounding them, but did not extend as far west as the Great Lakes or as far north as Rupert's Land.
In 1774, the British Parliament passed the Quebec Act that allowed Quebec to restore the use of French customary law (Coutume de Paris) in private matters alongside the English common law system, and allowing the Catholic Church to collect tithes. The act also enlarged the boundaries of Quebec to include the Ohio Country and part of the Illinois Country, from the Appalachian Mountains on the east, south to the Ohio River, west to the Mississippi River and north to the southern boundary of lands owned by the Hudson's Bay Company, or Rupert's Land.
Through Quebec, the British Crown retained access to the Ohio and Illinois Countries even after the Treaty of Paris, which was meant to have ceded this land to the United States. By well-established trade and military routes across the Great Lakes, the British continued to supply not only their own troops but a wide alliance of Native American nations through Detroit, Fort Niagara, Fort Michilimackinac, and so on, until these posts were turned over to the United States following the Jay Treaty (1794).
Quebec retained its seigneurial system after the conquest. Owing to an influx of Loyalist refugees from the American Revolutionary War, the demographics of Quebec came to shift and now included a substantial English-speaking Protestant element from the former Thirteen Colonies. These United Empire Loyalists settled mainly in the Eastern Townships, Montreal, and what was known then as the pays d'en haut (high country) west of the Ottawa River. The Constitutional Act of 1791 divided the colony in two at the Ottawa River, so that the western part (Upper Canada) could be under the English legal system, with English speakers in the majority. The eastern part was named Lower Canada.