Guest blog post by U.S. Census Bureau Director Robert M. Groves 
On April 2, 2012 the Census Bureau did something unique, a once-in-a-decade action. Throughout all other times, we focus on keeping confidential the social and economic data that households and businesses provide us. Once every decade we release the individual records of a 72-year-old census. This year it was the 1940 Census .
Approaching that day, the buzz in the genealogy world was deafening; they have been waiting 10 years to fill in their family trees, to learn new things about their ancestors, and to expand their insight into their lives.
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.
While the 2010 Census only had ten questions, the 1940 Census asked over 40 for some persons. It used sampling for the first time in the country’s history, asking a 5 percent sample of persons more questions than others. Instead of mailed questionnaires and other modes of data collection, all persons were enumerated by interviewers who visited each home, recording the attributes of each person on a line on big sheets of forms. Genealogists will learn their ancestors' age, sex, race, and relationship to the householder, as well as the value of the home, the highest grade of school completed, place of birth, and citizenship, and whether he/she was living on a farm, was married, and attending school. 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’s a treasure trove of ancestral attributes that we’ll all soon be able to review. Each census gives gifts to the country twice–once, when the aggregate statistical information is released soon after data collection, then, 72 years later, when individual forms are released for historical and genealogical purposes.
For more information on the 1940 Census, please visit http://www.census.gov/1940census/index.html .