Which is the best description of how physical geography impacted westward expansion in the united states? a) as the region became more and more populated, the way of life of the native americans changed. b) new land policies such as the homestead act of 1861 allowed “squatters” to claim land and keep it. c) travelers to the west had to cross not only the plains, but also major rivers, and the rocky mountains. d) after the civil war, the transcontinental railroad provided a way for those who had the means to travel to the west.