You could be a spy. You can't be too careful around those of unknown heritage...
At the fair, Lance Devlin brags about enlisting in the army. He mocks Ned for being too poor to enlist, then suggests that he might be an enemy spy since his ethnic heritage is unknown.
Many of the women in town are prejudiced against Miss Sadie due to her Hungarian heritage, accent, and clothing. They do not allow her to submit a square for the Victory Quilt that is to be signed by President Roosevelt.
Ned is taken away from his mother when they arrive in America. When Miss Sadie finally tracks him down years later, he has been adopted by an American family. Miss Sadie decides not to reveal her identity in order to spare him the humiliation and and prejudice she experiences.
Shift ends at midnight, when the Italians get here.
The 1917 flashbacks begin with Jinx and Ned running into a KKK rally. The KKK is strong in Manifest because of its large immigrant population. The klan members object to the different races, nationalities, and religions of the immigrants.
Arthur Devlin takes advantage of the immigrants' need for work by making them work long hours for low pay. He encourages tension between ethnic groups by refusing to let different nationalities work together. He hopes this will prevent them from working against him.