Thank you for the question. I had a theory--still unproved--that, at least some places in Virginia, under the auspices of the American Colonization Society, a census was taken of all people of color which may be one model for the 1850 Censuses insofar as what information, or new information was collected compared to earlier Censuses. The only example I have ( I wonder if this is true for other places) are two censuses taken circa 1833 in St. Anne and Frederickville Parishes in Albemarle County, Virginia. Again it was under the ACS that this specific information was gathered. I have searched microfilm of 1840, 1830, plus a few earlier census schedules and they are quite different than 1850 and these particular documents (also note the year). Futhermore, Mr. Ervin L. Jordan, Jr. wrote about these cenuses in the Magazine of Albemarle County History circa 1995.