Pretty sure it was because of huge war reparations.
It was "John O'Sullivan" who <span>entitled the phrase "manifest destiny," since he used this phrase to describe the vision that the US was "destined" to expand all the way to the Pacific Ocean. </span>
According to today’s historical theories, Native Americans first migrated to the Americas over "<span>d. 15,000" years ago, although closer estimates put the time closer to 13,000 years ago. </span>