Factors of environment makes people in west to settle and shape their lives at Mississippi:
The Western part of the river was filled with fertile pieces of land which attracted a lot of farmers and miners. They ended up settling along the banks of the river. Apart from fertile land the banks were also filled with minerals too.
After settling, the lives of the people changed drastically such that they were dependent on the river for their livelihood but the population was unevenly spread across the river too. This was followed by the development and expansion of railways which speed up the process.