Answer:
The support for the white supremacist groups increased during the 1920s because wartime propaganda increased suspicion of people perceived as lacking in patriotism.
Step-by-step explanation:
All the war propaganda during the 1920s was loaded with lots of patriotism and demanded citizens to respect and defend who they were as society, this opens the door to the supremacist groups exposing their point of view as a way to be patriotic and to keep their nation clean and free, the propaganda didn't only punish political opinions but also genetic heritage.