When it came to the Congress to approve the joining of the United States in the League of Nations it was blocked by the Republican opposition, especially from Senators William Borah and Henry Cabot (D).
The U. S. public opinion was still disappointed over the outcomes of the war. Also, the Republican Senators did not like what they thought to be a violation of the U.S. sovereignity: the covenant of the League in it's Article X predicted that in case of a member being attacked all the others should defend it.
This added to the historical isolationism of U.S. diplomacy stopped the country from joining the League of Nations despite its inspiration on President Woodrow Wilson’s Fourteen Points.
People did not need to travel for food, crops were domesticated for people
Hitler committed suicide so he didn't get captured by the allies.
Not slave, Kansas is middle north of North America but I do believe it was a free state
Western Europe valued imperialism. For example, Great Britain was known for the numerous colonies that they had. There is a quote that states, "The Sun never sets on Great Britain" meaning that they had so many colonies around the world that the Sun never set on them. In addition, countries such as France and Spain also imperialized especially in the New Worl. However, Eastern Europe was always less developed than Western Europe so they didn't have the power to colonize countries. I hope this help! Good luck!