Series: M252   Rolls: 1 - 71 1810 Facts 1. Third U.S. decennial population census. 2. U.S. population: 7.2 million     (6.0 million free, 1.2 million slave) 3. Census conducted by U.S. marshals under the     direction of the Secretary of State. 4. Census day: 1st Monday in August (6 August 1810). 5. Mandated copies: One set, sent to the federal district     court. Same copy ordered sent to the     U.S. Secretary of State in 1830.