The decision of the United States to get involved in the war had very serious consequences on the population, in various different ways.
One effect was the damage it caused to families. The country relied primarily on conscription in order to get more soldiers involved. This meant that many families were separated, and that the number of widows and orphans grew after the war.
Another effect was the rise of censorship. The government was nervous about discourse that was critical of the war effort, so they passed several laws such as the Espionage Act of 1917 and the Sedition Act of 1918 in order to restrict free speech.