The Selective Service Act of 1917 was a pivotal piece of legislation in U.S. history, enabling the government to draft soldiers during World War I. Army Registration Day, held on June 5, saw the first wave of young men aged 21 to 30, later expanded to include ages 18 to 45, registering for military service. The day was marked by a nationwide effort, with registration sites in towns and cities across the country, and officials reported that approximately 10 million men registered, demonstrating overwhelming participation from the public. The event was characterized by a sense of patriotism, as citizens were called upon to fulfill their duty to the nation.In the aftermath of Army Registration Day, the Selective Service System evolved, with local draft boards established to manage potential soldiers. The government's goal was to enlist around 1 million men for deployment, and within a year, over 2.8 million men were drafted into military service. With a generation of men sent into combat, the registration efforts not only reflected the urgency of the situation but also indicated a significant shift in American society toward participation in international conflicts. The ability to conscript soldiers was transformative, as it allowed the U.S. to build a large fighting force almost overnight.This large-scale mobilization had long-lasting effects on American military policy and public perception of military service. The experience would serve as a model for future conflicts, establishing a precedent for the use of conscription. Additionally, it heightened discussions regarding the role of government in mobilizing citizens for war, a theme that has resurfaced in U.S. history during later conflicts, including World War II and the Vietnam War. The legacy of Army Registration Day continues to influence discussions about patriotism, duty, and the balance between individual rights and governmental authority.