Why did congress pass the selective service act during world war 1?

Congress passed the Selective Service Act during World War I in 1917 to address the urgent need for military personnel as the U.S. entered the conflict. The act established a system for conscription, allowing the government to draft men into the armed forces to ensure adequate troop levels. With millions of soldiers required for combat, the legislation aimed to quickly mobilize and train a large army to support the Allies. This marked a significant shift in U.S. military policy from a volunteer-based system to one that included mandatory service.