Answer: open new markets.
Explanation:
The greatest priority of western railroad development as illustrated above was to open new markets.
Connecting the coasts made exportation easier to the Eastern markets. The development of the railroad also brought about new economic opportunities and new territories were also easily accessible.
1. disease brought by colonists was a major factor. Kills millions
2. violent conflicts between the colonists and/or British forces against the natives
3. The westward expansion (there's a special name for it) Colonists kept colonizing deeper and deeper into the mainland until reaching the western sea coast. killing 10's of thousands on the way there
*millions died, possible around 10 mill
