The correct answer is increase in industrialization.
Due to the technological advancements of the mid-late 1800's, Americans started to rely more on industry rather than farming. Working in a factory rather than a farm had its perks. People who worked in a factory had guaranteed wages, whereas in farming the amount of money a person makes is dependent on several different factors like the amount of people who want to buy your products, climate, location, etc.
There wouldn't be a USA, and...
the Indians would still have pretty much all of the Middle-west of the USA.
Hawaii would still be under their kings/queens
Alaska would still be part of russia
China would pretty much never had any technological progress (they isolated themselves)
Japan would still be going around with pretty much katanas.
etc etc
if you want more i can give you more (if you want information on why one is on the list, post it in the comments)
hope this helps
The Entente-UK, Canada, Australia, British Malaya, British Raj (India) ect
The central powers- Germany, Austria-Hungary ect
Answer:
Atlantic Ocean and Indian Ocean
