By right of a 1957 ruling, the United States releases individual census reports to the public 72 years after the Census is completed. This means that each year that ends in “2” sees a new Census data set released. On April 2, 2012, we will release the 1940 U.S. Census of Population and Housing.  It is an odd event for an organization devoted to keeping every data record we collect confidential, in fulfillment of our strong laws protecting those data.

The 1940 Census data are of key interest to genealogists around the world, as they use them to make more discoveries about their family tree. Over the past decade, there have been enormous advances that help genealogists pursue their passions of tracking down their family histories. Census forms around the world have been digitized and indexed, so that it is common now to enter into web site the name of your ancestor and a few bits of other biographical details and within a few clicks see the digitized image of the census form that captured a description of an ancestral family unit.

Of course, there’s an interesting contrast between mounting a modern census in the U.S. and serving the genealogy community.  In the 2010 Census, we attempted to reduce the burden of responding to the census to a bare minimum required by law.  We touted the motto “ten questions, ten minutes” to promote participation of a busy America. When genealogists look at a Census form, they want to know as many things about their ancestor as possible. They like the Censuses with many questions, not those with few!

The 1940 Census is a unique Census in our history – the first to include questions that were asked only of a subset of the population, chosen through a near-random scheme.  Information on persons enumerated was entered on a large sheet containing 40 lines.  Two of the lines were designated to receive “supplementary questions,” about parental place of birth, language spoken in the childhood home, veteran’s status, enrollment in Social Security, usual occupation and industry of employment, and for currently or formerly married women, whether they were married more than once, age at first marriage, and number of live births. There were 15 supplementary questions, not counting a rewriting of the person’s name.

In addition to the questions on age, sex, race, and relationship to the householder were questions about the value of the home, living on a farm, marital status, attending school, highest grade of school completed, place of birth, and citizenship. For persons 14 years and older, there were additionally seven different questions on working status, current occupation and industry, number of weeks worked, and income. There were 34 separately numbered questions before any supplementary questions were asked.

In addition, simultaneous with the 1940 population census, there was the first housing census, with 31 questions on the nature of the structures. (Unfortunately, these forms were destroyed and are not part of our release on April 2.)

All told, the 1940 Census asked a lot more than the “ten questions” of the 2010 form!  We’ve reduced the total burden on the population from the Census, using modern sampling techniques. Now, only about 2 or 3 percent of the households each year are asked to respond to the American Community Survey, which has housing and detailed population attributes. Instead of every-ten-year estimates, we have annual estimates.

Some things stay the same. On the form were the words, “Your report is required by Act of Congress. This Act makes it unlawful for the Bureau to disclose any facts, including names or identity, from your census reports. Only sworn census employees will see your statements.  Data collected will be used solely for preparing statistical information concerning the Nation’s population, resources, and business activities. Your Census Reports Cannot be Used for Purposes of Taxation, Regulation, or Investigation.” Issues of confidentiality and limitation to statistical uses only were part of the 1940 census as well as the current one. However, in March of 1942, the War Powers Act reversed this, directing the Census Bureau to release individual data in support of the war effort until the law lapsed in 1947. That episode is a reminder to us to be vigilant about preserving laws that protect the confidentiality of data collected for statistical purposes, one of the bedrock principles of statistical practice in a democracy.

As the genealogist of my family I can’t wait to look up my grandparents, aunts, and uncles, as well as my parents’ forms. The forms won’t be indexed by name immediately, so we’ll have to link addresses of our ancestors to enumeration districts and then browse the enumeration district looking for our relatives. Right now, my tracking of the Groves’ family goes back to 1670 on the Isle of Wight, off the coast of England, but it ends in 1930. The 1940 Census allows me to see records of people I remember meeting in my youth.

To my fellow genealogists, I wish you happy hunting!