Final answer:
The Sacco-Vanzetti trial was significant as it symbolized Red Scare fears and the potential bias in the American justice system against political and social minorities, contributing to a division in public opinion and international criticism.
Step-by-step explanation:
The significance of the Sacco-Vanzetti trial was that it symbolized the fears of the Red Scare and highlighted the American justice system's potential bias against immigrants and those with radical political beliefs.
Despite little direct evidence connecting Nicola Sacco and Bartolomeo Vanzetti to the robbery and murder they were charged with, their anarchist affiliations and the anti-immigrant sentiment of the time played a significant role in their conviction and subsequent execution.
This case demonstrated the extent of the Red Scare throughout the 1920s and showed the divergence in perception of the trial based on racial and ethnic backgrounds.
It also raised questions about whether defendants were being tried for their actions or their political and social backgrounds.