That’s right, two Presidents of the United States were once slaves. Well the term was actually indentured servants. What’s the difference you ask? Indentured servants were bound by a contract to work for a master, who, in effect, owned him for the term of the contract.
When they were boys future Presidents Millard Fillmore and Andrew Johnson were both indentured servants.
Johnson was indentured to a tailor but ran away. The tailor offered a $10 reward for his return in the Gazette of Raleigh, North Carolina. No one ever collected the reward though.
Fillmore was indentured to a clothmaker and served his master for several years. He would eventually buy his freedom which cost $30.