It gave Kenya and many other country's in Africa by helping spread African-Americans all over the world.
Yellow fever.
after the Spanish War, the most caused deaths by 80% was of yellow fever.
Potential rate of return on investments and the level of risk are directly correlated. In general, if the level of risk of investment increases, the amount of potential return increases as well. As investors move up on the 'pyramid of investment risk' the chances of losing increase along with the amount of potential return.
Robbery and murder where very common on the road to the west. Coming across food was rare. Many people froze or starved on the road.
But while it was terrible for most, a lot brought along pigs, chicken, wheat, and other eatable things to last them the trip. This was useful and could make for a better experience. You could tell why you and your family are traveling west, is it for a better life or do you have family over there? Where are you going? Are you rich or poor? How old are you? What is your family like, these factor in.
They created the valleys because they pulled them downstream