Earlier quoted context omitted.
There are certainly political threads. American westward expansion had to be justified, for example, by claiming cultural superiority over the people who were being displaced.
Most of the Americans who did the actual westward expansion didn't bother with justification. They saw the land was lightly populated and took it.
See this summary linked here and copied in full below: https://homework.study.com/explanation/how-did-americans-jus...
"How did Americans justify westward expansion?"
"Americans justified westward expansion through the ideology of Manifest Destiny. Manifest Destiny was a term coined in the mid-1840s. It claimed that the United States was providentially designed to spread across the continent. Believing their "civilization" to be superior to Native and Mexican peoples, it supposed their lands should rightfully be part of the United States. This led to the brutal subjugation of Native tribes as millions of Americans flooded west in the decades after the Civil War."