That time period in US history is really important. I would definitely recommend taking it.
During that period we saw the establishment of Jim Crow, the rise of jingoist nationalism, and the desire for overseas imperialist conquest.
It was also one of the most violent and turbulent political time periods in our history with massive labor strikes, violent responses to those labor strikes, anarchist terrorist plots, assassinations, bombings, massive corruption, populism, women's rights movements, temperance movements, etc.
After that, we begin to see the rise of progressiveness in response to the corrupt corportist/laizzee fair government that we had before. This is an extremely important period because we get to see how America dealt with the huge dislocations of industrialization that gave enormous wealth to business leaders, put millions in squalid working conditions in a factory and not on a farm, and how this new wealth influenced and shaped our politics.
Progressiveness was not without its problems because they largely favored everything scientific and what was scientific at the time was also scientific racism, social darwninism, and eugenics. The connections to these ideas and Hitler/WWII are pretty obvious. I think this is important because we shouldn't pretend that these ideas were not accepted anywhere else besides Germany. Hell, even pogroms against Jews were rather common in Europe, especially Eastern Europe and Russia before Hitler took power.
My other choices would be Women's history and Germany