Final answer:
The Civil Rights Act of 1866 was significant because it declared African Americans to be citizens, challenged the Black Codes, and empowered federal intervention to protect citizens' rights, setting the stage for the Fourteenth Amendment.
Step-by-step explanation:
The Significance of the Civil Rights Act of 1866
The Civil Rights Act of 1866 was monumental as it established the citizenship of African Americans, providing a significant step that countered the Supreme Court’s Dred Scott decision. This legislation gave the federal government the authority to intervene in state affairs to protect the rights of citizens, especially African Americans. It attacked the Black Codes and laid the groundwork for the Fourteenth Amendment, which solidified the concepts introduced by the act into the Constitution. The Civil Rights Act of 1866 was notable for being the first act passed over a presidential veto, illustrating the strength of congressional support for civil rights during this period.