Are black population harmonized in the early census?


When I look at the black population in my county (Fairfax County, VA), they were account for about 10% in 1850 and 1860 censuses, then suddenly increased to 40% from 1870 to 1900, and slowly going down to about 10% by 1960. I read somewhere the slaves were counted as 3/5 of residents in the early days. I wonder if this is the reason why black population was so low in 1850 and 1860 census when comparing to the years right after that. Does IPUMS harmonize black population in the early census so that they can be counted as a full person? if so, how does this harmonization work? by person’s weight or something else? Kindly advice. Thank you!!


In the earliest available census samples, available via IPUMS, the samples are drawn from a universe of household enumeration schedules. This means that the slave population will be missing from these files. This detail is noted on the sample descriptions page. With that said, IPUMS USA does provide files that contain data from the slave schedules. They are available here.

Regarding sample weights, here is a potentially helpful discussion in this blog post. In sample data from IPUMS USA each person within each sample represents more than one person in the overall population. Therefore, the sampling weights allow for an adjustment so that statistical calculations using sample data can be representative of the larger overall population. Alternatively, you can use the full count data, available via IPUMS USA, where each individual in the overall population can be found in the data.


Hi Jeff, Thank you so much!!