I don't find more than one or two former slaves out of the 86 "other free" heads of household in the 1810 census of North Carolina for Northampton and adjoining counties [http://www.freeafricanamericans.com/1810NCc.htm].
The increase in Northampton County appears to have been natural increase of the population from 1790.
1790: 462 "other free"/ 5110 whites 
1800: 539 "other free"/ 5605 whites
1810: 580 "other free"/ 5824 whites

 North Carolina laws of 1778 and 1796 allowed emancipation only in the case of "meritiorious services, adjudged and allowed by the county court"--though this was interpreted liberally in counties with large Quaker populations [See Byrd, In Full Force and Virtue: North Carolina Emancipation Records, 1713-1860].
Paul
http://www.freeafricanamericans.com/http://www.freeafricanamericans.com/

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