Westward expansion meant that the US acquired ever increasing amounts of land, and needed people, farmers, to settle there so it could maintained without a huge military presence
C. railroad...............
It causes for the world climate to rise causing global warming. Also erosion causes be buildings to be eaten away from water or acid rain and can destroy homes and possible hurt humans. Deposition runs into the water and streams with eventually goes to the water lines to the food and drinks we consume today.
