The assassination of President William McKinley in 1901 was executed by Leon Czolgosz, an unemployed steelworker who held anarchist beliefs. The attack occurred during the Pan-American Exposition, a world's fair held in Buffalo, New York, meant to promote trade and cultural exchange with countries across the Americas. On September 6, as McKinley stood greeting the public, Czolgosz took advantage of the moment and fired two shots, hitting the President in the abdomen and chest. The assassination shocked the nation and drew widespread attention to the rise of anarchist sentiments in the United States.

Following the shooting, McKinley was rushed to the hospital, and initial reports indicated he might survive the ordeal. However, his condition deteriorated, leading to his death eight days later. The event had profound repercussions. McKinley's funeral was a significant national occasion, attracting attention from millions across the country. In the wake of the assassination, Vice President Theodore Roosevelt was sworn in, heralding a new era in American politics characterized by progressive reforms and a more assertive foreign policy.

Czolgosz was swiftly apprehended, tried, and ultimately executed in the electric chair. His trial highlighted tensions between government authorities and individuals expressing radical political beliefs, igniting discussions on social justice, labor rights, and the use of violence as a means of political expression. Ultimately, the assassination marked a turning point in the approach to political violence and the security protocols surrounding American presidents.