It Was a 7: One 1940 Census Code Revealed

Post-enumeration coding of 1940 census data for marital status

Like many over-eager genealogists, I was online the morning of 02 April 2012 – the first day the 1940 census was available to the public. Within a matter of days, I had located a handful of relatives on the 1940 census by first locating their enumeration districts. It wasn’t long before I began finding information in this census that I hadn’t encountered previously despite having done extensive census research in the past. For example, why was I finding the numeral “7” in the marital status column, instead of one of the more common abbreviations of marital status, such as S[ingle], M[arried], W[idowe]d or D[ivorced]?

1940 census with marital status column 12 highlighted1940 U.S. Federal census entry for Oliver Bingaman of Shoshone County, Idaho.

I’ve highlighted column 12 in the 1940 census in red where marital status was recorded. Note those who reported they were married (M) where the M was crossed out and a 7 penciled in. As we shall see later in this piece, instructions to enumerators were only partially followed for this household. In the case of the author’s grandfather, Oliver Bingaman, highlighted in yellow above, no obvious wife was enumerated with him, and yet there was no alteration of his marital status as originally recorded.

Fortunately, I was able to track down a blog entry by Meldon J. Wolfgang III, wherein he described this very scenario, and some of the backstory behind this particular census code. Read his post here.

Mr. Wolfgang’s blog entry contains a link to a very valuable resource: the IPUMS-USA website. Wolfgang explains

“IPUMS is not a genealogy site; it is the acronym for the ‘Integrated Public Use Microdata Series’ and is part of the University of Minnesota’s Population Center. Data geeks, statisticians and epidemiologists – all of whom use census data – are the primary users of this site.”

Even though genealogists per se are not the intended audience, serious genealogists will nevertheless find a wealth of information about the decennial United States Federal census on this site.

IPUMS USA website

IPUMS-USA census data website –

To locate the procedural history that explains the post-enumeration coding done by the staff of the Census Bureau, navigate to this link:

It is under the General Population Coding section that we find the explanation for the coding of marital status:

Source: Jenkins, Robert M. Procedural History of the 1940 Census of Population and Housing. (Madison : University of Wisconsin Press, 1983), p. 63

To summarize, if the enumerator left the marital status column blank, then the Census Bureau staff in Washington D.C. would attempt to complete the field based solely on other elements they read on the page. If no spouse or children were living in the household, the coder assumed the individual was single. If, however, the person had no spouse in the home and there were children present, then one of two codes was entered, either 1) widowed, if the individual was 55 or older, or 2) 7, if the person was under age 55. Even when a marital status of M[arried] was recorded, clerks were instructed to interline the M and replace it with 7 if no spouse was included in the household, thus resulting in this entry: M 7. This distinction with respect to age is important. In a nutshell, if you find a marital status of M crossed out and replaced with Wd, don’t assume the spouse is deceased; look for that individual in another household. If you find a 7 in the marital status column, or an M crossed out and a 7 penciled in, then look for the spouse in another household.

As Wolfgang pointed out in his post, the census coders had no special insight into any particular household. If something you’re seeing in the 1940 census doesn’t track with research you’ve done on a family, or with your own personal knowledge of events, then having a better understanding of these codes may help explain any anomalies.

We have examined a bit of the history of census coding for a single column of data (marital status) in a single census year (1940). Imagine what additional information you may be able to glean from other entries if you read the relevant instructions or procedural history as well. The IPUMS-USA website is a great place to start.

Note: In his blog post, Meldon J. Wolfgang III referenced a talk he gave in the days leading up to the release of the 1940 census. Judy G. Russell, CG, (aka the Legal Genealogist) was in the audience and gave a brief synopsis of his talk, and an overview of the IPUMS-USA website, on her blog.

1940 Census Indexing Update

The Genealogy Insider blog by Diane Haddad on April 10th gave us a nice update on 1940 census indexing to date by various entities. I was intrigued by the beautiful map on the 1940 census page, showing percent completion of indexing efforts state by state. Place your cursor on any state to view how much of that state’s census has been indexed. Below, you’ll see that 92% of the 1940 census for Kansas has been indexed  by volunteers in the ten days since the census was released. Amazing effort!

Map of U.S. showing census indexing efforts to date

It is important to remember that this map represents indexing efforts of one group only. If you don’t find your state represented, check out some of the other links in Haddad’s blog to see what has been done by other groups. Join the volunteer indexing effort at

Another Infographic About the Release of the 1940 Census

If you’re interested in statistics about the public launch of the 1940 United States Federal Census, or you’re just a data nerd in general, you’ll find this infographic released by to be an interesting glimpse behind the scenes. The first digital release of the census was clearly a massive undertaking, with wide-spread public appeal.1940 census