1) The Red Scare refers to the fear of communism in the USA during the 1920's. There were over 150,000 anarchists or communists in USA in 1920 alone and this represented only 0.1% of the overall population of the USA. However, many Americans were scared of the communists especially as they had overthrown the royal family in Russia in 1917 and murdered them in the following year. The fear of communism increased when a series of strikes occurred in 1919. Throughout the 1920's and 1930's a culture developed within America which both feared and despised communism.
Examples of the Red Scare are in 1901, an communist had shot the American president (McKinley) dead. The Boston police went on strike and 100,000's of steel and coal workers did likewise. The communists usually always got the blame. A series of bomb explosions in 1919, including a unprofessional attempt to blow up A. Mitchell Palmer, America's Attorney-General, lead to a campaign against the communists. On New Year's Day, 1920, over 6000 people were arrested and put in prison. Many had to be released in a few weeks and only 3 guns were found in their homes. Very few people outside of those arrested complained about the legality of these arrests such was the fear of communism.
However, far more people complained about the arrest of Nicola Sacco and Bartolomeo Vanzetti. They were arrested in May 1920 and charged with a wages robbery in which 2 guards were killed. Both were known to be communists and when they were found they both had loaded guns on them. The judge at their trial - Judge Thayer - was known to hate the "Reds" and 61 people claimed that they saw both men at the robbery/murders. But 107 people claimed that they had seen both men elsewhere when the crime was committed. Regardless of this both men were found guilty. They spent 7 years in prison while their lawyers appealed but in vain. Despite many public protests and petitions, both men were executed by electric chair on August 24th, 1927.