What historical event is associated with the onset of the "Red Scare" in the United States?

The onset of the "Red Scare" in the United States is primarily linked to the establishment of the Soviet Union in 1922 and the broader context of the Russian Revolution in 1917. This period was characterized by heightened fears of communism and radical leftism, especially in the wake of World War I when societal tensions were high. The creation of a communist state in Russia and its subsequent advocacy for international communism led many Americans to fear that such ideologies could infiltrate or threaten the United States.

During this time, numerous events contributed to the climate of fear, including labor strikes, domestic unrest, and the growth of socialist movements, which many associated with the potential for a communist takeover. The government's response to these fears included the Palmer Raids, where suspected radicals were arrested and deported without due process. This response was fueled by a combination of genuine alarm over potential threats and prevalent xenophobia, as many of the individuals targeted were immigrants.

The other options, while important historical events, do not have the same direct connection to the emergence of the "Red Scare." The Great Depression occurred later and stemmed from economic collapse rather than political ideology, while World War I is more a backdrop than a direct cause. The Civil Rights