There have been many incidents in the history of the United States that placed fear in the minds of many Americans. Two major events of this nature occurred from 1919-1920, and again from 1947-1957. What caused these waves of fear? The answer is communism. The Red Scare was a period in which many Americans feared that communism would thrive, and the capitalist system in the United States would be threatened. Students can learn about this important part of history by delving into its causes and effects.