The American entry into World War I affected it because It led to more than a million United States troops aiding the Allied cause by 1918.
When the United States finally joined the war in 1917, thousands of soldiers were sent to Europe.
This number gradually increased until more than a million American soldiers were fighting in Europe in 1918 which led to the Central Powers collapsing.
Find out more on the U.S. entry into WWI at https://brainly.com/question/376104.