It would be communism and dictatorship. It is contrast why the allied powers fight for during the Second World War for a free and a democratic world but such dreams in the eastern Europe is lost because they are under the iron curtain of the Soviet Union after the war and become satellite states of USSR.
The industrial revolution helped with all of the above
To reduce the influence of Spanish/Portuguese colonizers in the region so the USA could be considered the only major power in that area.
A. We know the cities during the industrialization changes were not very clean but we knew that there was a lot of people living there.