Could someone please help with these questions?

How has history between 1865 and 1945 shaped our current society?
I know that history between 1865 and 1945 gave the people of America the ability to grow and become a more knowledgeable nation. I feel that it was also a time in history when the American people took a stand and united as a whole nation.
How might our society be different without the advance or changes of events that happened in history between 1865 and 1945?

2 answers

During those years, the U.S. asserted its world dominance, helping win WWI and WWII.

During the 1800s, the U.S. expanded across the continent. It also extended its power and influence globally. Don't forget the influence of the airplane.

Might we be a racially segregated and isolationist nation if it weren't for the events in that hundred years?
To expand, we would most likely be isolated since US people did not wish to take part directly in foreign affairs.