the 1940 federal census record for my dad's family is 100% accurate for the entire family - names spelled correctly, ages correctly listed - for 2 parents and their 4 children. But the census also lists a 5th sibling, said to have been born in 1936, and so listed as being 4 years old at the time of the census. I have not provided you with names because I know you don't publish personal info, but the census also provides the 4 year old's name. My dad and all his living siblings say no such 5th sibling ever existed and say they know nothing about him. I have briefly searched for IA (where they lived) birth certificates and found nothing. No cousins by the listed name apparently existed. The father of the household worked on the railroad so if a 5th child did exist, he could have been born outside of IA.

Can you offer any insights, or suggestions of sources I could check?

Are errors like this - adding an entire person, not just a typo or spelling mistake - in census data common?

  • Is there a child of the same name and age on another family in the same page? If so, perhaps the person who wrote the record lost track of where they were transcribing from.
    – PolyGeo
    Jan 29, 2019 at 4:02
  • 2
    Question for mods: This is the sort of case where we really need to be able to see the page in question. Yes, it's got living people on it, but it's public information available to anyone. Is it reasonable to provide a pointer to it or is that still against the rules?
    – Cyn
    Jan 29, 2019 at 16:10
  • @Cyn I had the same thought when I read this question. It would be a good question to ask at Meta G&FH SE.
    – PolyGeo
    Jan 29, 2019 at 21:12
  • @PolyGeo I have created a Meta question. Thanks for the idea. genealogy.meta.stackexchange.com/questions/3408/…
    – Cyn
    Jan 30, 2019 at 1:39

2 Answers 2


Here are the questions that I would investigate, that might help determine who this extra household member was:

  • Have you looked at the census page image to verify it was indexed correctly? This is the most frequent issue.
  • Are there any notes in the margin beside this entry, that point to another page or another family? Indexers almost always ignore these, leading to annoying household mashups or random individuals not attached to the correct household.
  • Is the household's informant marked (specific to 1940 US census)? If it was a parent, they should know who they are giving information on, although errors can be introduced by the enumerator or later copyists.
  • Is all the information for the individual consistent with the rest of the family?
  • Is this 5th child listed after the rest of the family? Are the ages all in sequence?
  • Is it possible biologically (mother's age, intervals between pregnancies, etc.) for this individual to be a child of the family?
  • You've looked for birth certificates: what about death certificates? A 4 year old with older siblings shouldn't have been forgotten, but an early death should be checked
  • You have already investigated possible cousins: could it have been a child's friend or neighbour's child over for a sleepover or for babysitting? It does happen that surnames are sometimes applied across the whole household in error. The relationship should be indicated, but that's any easy error to introduce.
  • Not possible (yet) in this case, but if there had been an later census (state or federal) or the child older, I would also check the family in other censuses to see if the individual was still with them. I've seen lodgers become foster children become adopted children. And orphaned children raised by grandparents or other relatives.
  • This a strong answer that covers all the bases.
    – Cyn
    Jan 29, 2019 at 16:11
  • The 1950 Census will be released on 1 Apr 2022 -- not very long away now.
    – Jan Murphy
    Jan 30, 2019 at 1:04

I think it's important to remember that for genealogy, the historical records we use were created for another purpose. Understanding that purpose is key to getting the most out of the information inside our sources.

You can learn more about the 1940 Census by looking at research guides like the offerings at The US Census Bureau or the US National Archives, or by reading the reports at IPUMS-USA. Articles like Claire Kluskens' "Who Talked to the Census Taker?", while focusing on earlier census years, can also provide insight.

Have you read the enumerator instructions? You can download a PDF from the Census Bureau or read them online at IPUMSUSA.

Have you researched the enumerator for that neighborhood? Do you see irregularities in the other entries for that ED? US Newspapers are full of gossip, and articles can give clues about whether enumerators were of sound character, or may have issues that would interfere with their attention to detail.

Most important of all -- examine your own hidden assumptions. Everyone makes assumptions without being aware of it. Part of being a good researcher is dragging those ideas out into the light of day. Without being aware of it, we might assume:

  • that a record set is complete
  • that a record set is accurate
  • that the enumerator always followed the instructions
  • that the informant understood the question that was asked
  • that we understood the role of the enumerator

Today's Genealogy Tip of the Day In What Capacity Does Their Name Appear? is relevant to an enumerator as well as notary public.

Sometimes the only way to set your mind at ease about unexpected things in a record is to researched thoroughly the people involved in the records, starting from scratch, with no preconceptions. I've seen several examples in my own census research where it quickly became evident that these "surprise" people belonged with families who are enumerated on the same sheet or on nearby pages.

In an obituary, I found a list of bearers at a funeral who were listed as nephews of the deceased, but my prior research had already shown that they were the deceased's grandsons. If I had come across that obituary first, trying to prove that they were nephews would have sent me off on a long, fruitless line of research.

Because of these experiences, and others, my standard procedure is to assume that the person may not have the relation to the head of household which is stated in the census. I ask "How can I find out more about people named [name] born in [location] around [calculated birth year]?" and go from there, starting with finding out how many same-name candidates there might be for that question. I do this in addition to all the good suggestions that were made in the previous answer.

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