Manifest destiny is a concept meaning that the United States has a God-ordained right and purpose for taking over the breadth of the North American continent. Champions of this idea started parading their belief that they were bringing civilization and structure to an unruly wilderness by settling throughout the West.

This concept gave white Americans justification for their desire for expansionism. The Americans pushed westward and tried to take hold of as much land as possible by whatever means they could reasonably justify. This ended up with American spreading all the way to the current border of Canada as well as to the Pacific Ocean.

There was, in fact, a great desire to take over Canada as well, because many people saw it as their right to stake a claim on the entire North American continent. After the American acquisition became a little too difficult to maintain with the current population, white colonizers slowed down their efforts and claimed that they had completed God's will for America.

This entire concept was essentially a justification for the American nation's desire to conquer everything around it. It gave them an excuse to do what they already desired and allowed them to go and seize control of the entire region.