Paul,

The Ancestry.com Home edtion has a feature (check box) in their African American Historical Record Collection that allows a census search (1850-1930) to show only results for those noted as people of color.

On Ancestry.com you may also request a census search for a specific year (1850) and use the Advance Search Options which in addition to Keyword, as mentioned by Hollis Gentry, allows for gender/color/ birthplace/year as search parameters.

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Paul wrote:

"Although names and races of free persons of color are found on the 1850 census roles, I find it difficult to search on Ancestry for free Black residents of Virginia in 1850. Are there any tricks to do that?"