Because they died, and many got sick
Mr. Butler says that the Great Depression affected him more than the Civil War because for him it the end of the country of the opportunities. For him the most heartbraking things were the thousands of people living on the streets with no job, no home, no food, the schools and churches being transformed into refuges for thousans of people. This were the matters that really affected him instead of the war itself.
Mainly for transportation purposes
I would have to say A) Lewis and Clarke expedition because Lewis and Clarke did explore the Louisiana Territory, The Treaty of Greenville happened before the purchase, and the other 2 had different causes.
