Anarchism in the United States was originally individualistic and free-thinking , as typified by the work of Henry David Thoreau , but was overshadowed by a mass , cosmopolitan , anti-hierarchical , working class movement between the 1880s and 1940s , whose members were mostly recent immigrants . The anarchist movement achieved notoriety due to violent clashes with police and assassinations , but most anarchist activity took place in the realm of agitation and labor organizing among immigrant workers , with the exception of the Industrial Workers of the World , whose members were mostly native-born Americans
assassinations
Assassination of William McKinley
American Left