There are many environmental problem. The country is rapidly industrializing and this causes things like deforestation and overpopulation. This in turn causes a lot of smog and air pollution to be everywhere, and the high density means all people are concentrated together in these polluted areas. There are also problems with getting fresh water for everyone because of the pollution.
1. They can be formed bcause of events
2. Cities can also grow on rivers to help grow the poupulation
African Americans gained freedom from joining World War 2