The document discusses several key factors that influenced the post-Civil War expansion and settlement of the American West:
1) Ideologies like Manifest Destiny and nationalism guided westward expansion, as the US sought to expand its territory across the continent.
2) New legislation like the Homestead Act of 1862 offered free or cheap land, incentivizing farmers to settle the West. Transcontinental railroads also promoted western migration.
3) Conflict arose as white settlers pushed onto lands inhabited by Native Americans, leading to a series of Indian Wars as the US military forced tribes onto reservations to make way for expansion.