Answer:
an epidemic of the "Spanish flu" struck the country
Step-by-step explanation:
After World War I, the military force (United State's troops) was not necessary anymore, so they were sent home. As a result of this, a new strain of Influenza virus emerged. It was called "Flu Pandemic" or "Spanish Flu." Since there was no medication against it, many Americans fell ill and died, only in a span of months after the war. The flu is said to have killed more Americans than in the World War I, thus it was considered the most devastating epidemic ever recorded in history.
It was hard for people to live a normal life, since they needed to protect themselves against the flu. This affected the people's social life. They preferred staying home, rather than meeting new people. Whenever they go out, they needed to wear some masks for protection.