The Clark Family in 1850, part 2

A Closer Look at the 1850 Census: Ages and Dates

How well does the information on the 1850 census schedule agree with the Clark Family Record and other Clark family documents and known facts?

First, examine the census page header. It was enumerated by J. I. Loomis (a resident of Polk township, Washington county) and covered the “Free Inhabitants in Mequon Dist. No 15 in the County of Washington State of Wisconsin enumerated by me, on the 7th day of Oct. 1850.”

CLARK, Jonathan family 1850 census (

“United States Census, 1850,” database with images, FamilySearch ( : 12 April 2016), J M Clark, Mequon, Washington, Wisconsin, United States; citing family 1120, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).

As in other U.S federal censuses, there was an official enumeration date; in 1850 it was June 1, 1850 (see column 3, header). But enumerator Loomis was not able to actually visit the area and write down the census information until October 7, 1850. So did Loomis enter the ages of the family members based on the June or the October date? It seems like a small matter, but it can cause difficulty when assessing the accuracy of this and other documents. So, using the  birth dates given in the Clark Family Record, let’s compare the census ages we would expect based on an official June 1st, 1850, census calculation versus the ages we would find on a “real date” calculation based on an October 7, 1850, enumeration date (ages given in Years/Months/Days format):

NAME                AGE on census      AGE as of June 1 1850      AGE as of Oct. 7, 1850

J M Clark                     38                           37y/6m/4d                           37y/10m/9d

Mary                            29                           30y/0m/28d                         30y/5m/3d

Caroline                        9                            9y/6m/25d                           9y/11m/0d

Henry                            7                            7y/3m/11d                           7y/7m/16d

Elizabeth                      5                             5y/3m/7d                             5y/7m/12d

P A                                 3                             2y/7m/27d                           3y/0m/2d

Mary                            5/12                         0y/0m/23d                           0y/4m/28d

So what to make of all this? Here are a few conclusions:

• In spite of what the government may have instructed, enumerator Loomis and his informant appear to have calculated the ages of each family member based on the actual day of enumerating this part of the district, October 7, 1850.

• For the two youngest Clark family members, Loomis or his family informant rounded up to the nearest year or month.

• For the ages of Caroline, Henry and Elizabeth, Loomis followed government instructions and rounded down to the nearest full year (although this was based on October 7, and not the official date of June 1).

• Mary’s age is rounded down to 29, even though she was 30 years old before June 1st.

• Based on a birthdate of November 28, 1812, Jonathan M. Clark’s age is rounded up to age 38. But if we calculate JMC’s age from November 28, 1811 (as suggested in one or two other sources), then his age on the actual date of enumeration, October 7, 1850, would be an actual 38 years, 10 months, 9 days. This makes JMCs possible birth year of 1811 more plausible, although the majority of JMC documents give 1812.

• If you are trying to calculate possible birth years of persons enumerated on the Mequon census in October, 1850, you might well assume that their ages have been calculated based on the actual—October—date of enumeration, rather than the official date of June 1, 1850.

And finally, what about Arthur Clark, age 16? More on him in a future post…

P. S. Measuring date-to-date was once a difficult and error-prone task. It’s amazing how often families and gravestone carvers got it right. If you’d like to calculate your own date-to-date durations —or check my calculations—here’s a link to a really useful calculator.