What is manifest destiny? Do you agree with that belief?

The 19th-century believed that the expansion of the US throughout the American continents was both justified and inevitable.

The 19th-century doctrine or belief that the expansion of the US throughout the American continents was both justified and inevitable. I personally don't agree with it because we killed many innocent lives to take over this land but the U. S. Wouldn't be the way it is today if we didn't.