Final answer:
The ruling in the Dred Scott case addressed whether African Americans, both enslaved and free, had basic citizenship rights.
Step-by-step explanation:
The ruling in the Dred Scott case was so significant because it addressed whether African Americans, both enslaved and free, had basic citizenship rights. In the case, the Supreme Court declared that Scott, an enslaved African American, had no standing to sue in federal court because blacks could not be citizens of the United States. This decision had far-reaching implications as it confirmed that African Americans were not considered citizens and therefore did not have basic citizenship rights.