United States 1940 Census data is now available online. Earlier Censuses were released on microfilm.
Some 132 million people took part. Along with questions about name, gender, age and relationship to head of household, education and salary, people were asked for the first time where they were five years earlier in 1935, Reuters reports.
Historians say it contains a treasure trove of information about people who survived the Great Depression.
There were only 48 states in 1940 and the average annual salary was $US1,299. James and Mary were the most popular baby names.
More than 100,000 online volunteers are now transcribing the census information into a searchable index for the 1940 US Census Community Project.
So far nearly 42% of the entire index of 132 million people is complete, including six states that are published. Ten more are about to be published and eight others are 50% or more complete.