First Red Scare was a period during the early 20th-century history of the United States marked by a widespread fear of Bolshevism and anarchism , due to real and imagined events ; real events included the Russian Revolution and anarchist bombings . At its height in 1919 – 1920 , concerns over the effects of radical political agitation in American society and the alleged spread of communism and anarchism in the American labor movement fueled a general sense of concern
anarchist bombings
1919 United States anarchist bombings
First Red Scare