What did dred scott base his claim freedom on?

His travels and residences in free areas.

Explanation:

The case Dred Scott v. Sanford was a landmark decision of the Supreme Court. In this case, Dred Scott, an enslaved black man, sued in court for his freedom. He argued that his owners had taken him from Missouri into the Missouri Territory, which was a "free" territory. The court ruled that Scott could not sue in court as he was not considered an American citizen due to his African ancestry, regardless of whether he was a slave or not.