The significant legislative act that abolished slavery in the United States was the 13th Amendment to the Constitution, ratified on December 6, 1865. This amendment officially outlawed slavery and involuntary servitude, except as punishment for a crime. The 13th Amendment was a cornerstone achievement of the Civil War and the broader abolitionist movement, fundamentally reshaping American society. It paved the way for subsequent civil rights advancements, though the legacy of slavery and institutional racism continued to impact the nation for generations, leading to ongoing struggles for equality and justice.