How did westward expansion impact US history 1840-1860?

Another alternate history (very detailed) is the Timeline 191 series by Harry Turtledove. The south wins the civil war, the two countries develop as occasional antagonists (similar to East and West Germany) Eventually the USA, with its greater resources, overwhelms the CSA in an alternative World War Two (the equivalent of the Nazis and Hitler show up in the South as opposed to Germany, with the holocaust perpetrated on blacks rather than Jews) Even if they had won the war, the southern states couldn't have survived long as an independent country, without becoming a client state for England or France. Slavery was unsustainable as an economic system, the central government as designed was very weak, and eventually world opinion would have forced the emancipation of slaves, causing the entire southern social system to collapse.

There would have been two countries and I don't know if both would have helped in World War I.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.