When the United States decided to participate in World War I, the civilian population was severely impacted in several different ways.
The most obvious one was the fact that young men were enrolled in the Armed Forces. This affected their lives deeply. Many soldiers died, and the ones who did not were often deeply affected and traumatized.
This also led to families being separated and many women being left in a vulnerable position. During the war, women were forced to take on a more public and active role, and this contributed to the development of feminism.