What was the impact of the westward expansion of settlers in the USA?

The following was the impact of the westward expansion of the settlers in the USA.

A. The westward expansion of the settlers led to displacement of local tribes. They were driven beyond river Mississippi and further west.

B. The settlers began agriculture on an extensive scale. They slashed and burin forests, pulled out the stumps, cleared the land for cultivation and built log cabins in the forest clearings. Then they cleared larger areas and erected fences around the fields. They ploughed the land and sowed corn and wheat. Thus, agriculture was undertaken at the expense of grasslands and forests.

C. The settlers continued moving further west to explore new land and raise a new crop. After the 1860s, the settlers reached the Great Plains across the River Mississippi. They started growing wheat and soon turned this region into a major wheat producing area of America.