The British Parliament's Act of Union of 1840 was a legislative measure that united the two British North American colonies of Upper Canada (now Ontario) and Lower Canada (now Quebec) into the single Province of Canada.
The Act of Union was passed in response to a number of issues that had arisen in the two colonies, including political unrest, economic problems, and cultural tensions between English and French-speaking populations. The British government hoped that unifying the colonies would help to resolve these issues, and create a stronger and more cohesive political entity that could better manage the territory and its resources.