Free black slaveowners resided in states as far  north as New York and as far south as Florida, extending westward into Kentucky, Mississippi, Louisiana, and Missouri. According to the federal census of 1830, free blacks owned more than 10,000 slaves in Louisiana, Maryland, South Carolina, and Virginia.
By 1800, one third of colored heads of households in 
Charleston,  South Carolina  recorded slave property. Between 1820-1840, the percentage increased to 75 percent. 
By 1850, the percentage had declined to 42 percent
http://www.uwec.edu/Geography/Ivogeler/w188/south/charles/charles3.htm