This document summarizes the key factors that led the United States to initially remain neutral in World War I but eventually enter the war in 1917. It discusses the economic reasons for neutrality due to American loans to the Allies and not wanting to jeopardize being repaid. It also describes the human toll of the war and desire to avoid U.S. casualties. However, events like the sinking of the Lusitania, which killed American citizens, and the Zimmerman Telegram proposing a German alliance with Mexico against the U.S. increased pro-war sentiment and helped push the U.S. into the conflict.