An argument can be made that that the Dred Scott decision made the U.S. Civil War inevitable. Previously, northern whites had been able to close their eyes to the existence of slavery, because it wasn't happening near where they were and they didn't have to see it every day.
But the Dred Scott decision destroyed that illusion. If a slaveowner from Missouri could bring his slaves to Ohio and set them to work, what could it even mean to say that Ohio was a free state? Even people in the north who didn't care about the moral issues had concerns about losing their jobs to slaves. What was there to stop a Missouri slaveowner from buying farms in Ohio and operating them entirely with slave labor?
“The decision of Scott v. Sandford, considered by many legal scholars to be the worst ever rendered by the Supreme Court, was overturned by the 13th and 14th amendments to the Constitution, which abolished slavery and declared all persons born in the United States to be citizens of the United States.”
https://www.archives.gov/milestone-documents/dred-scott-v-sandford
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