Final Answer:
The term for the fear of communism that spread across the United States during the 1920s was known as the "Red Scare."
Step-by-step explanation:
The "Red Scare" refers to the widespread fear and paranoia regarding communism that gripped the United States in the aftermath of World War I, particularly during the 1920s. The fear was fueled by the Russian Revolution of 1917, the rise of the Bolsheviks, and the establishment of the Soviet Union.
During the Red Scare, there was a heightened suspicion of leftist ideologies, labor movements, and perceived subversive activities. The government, led by figures like Attorney General A. Mitchell Palmer, took measures to suppress and eliminate what they perceived as radical influences, resulting in arrests, deportations, and infringements on civil liberties.
The term "Red Scare" encapsulates the anti-communist sentiment that permeated American society during this period, impacting politics, culture, and the lives of individuals.