Why did the Constitutional Act of 1791 divide Quebec into Upper Canada and Lower Canada?

The Constitutional Act of 1791 divided the province of Quebec into Lower Canada (modern-day Quebec) and Upper Canada (modern-day Ontario) primarily to accommodate the influx of United Empire Loyalists following the American Revolution.12

After the war, thousands of these loyalists settled in the western regions of Quebec. These settlers, who were largely English-speaking, desired English common law and representative government—institutions that were not provided under the existing French-influenced legal and administrative framework of the Quebec Act.32

By splitting the territory along the Ottawa River, the British government sought to satisfy the demands of the loyalists for land ownership and legislative representation while maintaining the established French civil code and religious practices for the French-speaking population in the east. The act also established elected legislative assemblies in both provinces, aiming to replicate the general principles of the British constitution.132