The National Archives website for and operating after it crashed Monday because of the massive interest in the newly released information.
"We have seen extraordinary demand for the 1940 Census records," according to a note at the top of the records page.
The 1940 Census offers a trove of data available online – about 3.8 million images - for anyone looking for family history or curious about the past.
About 132 million people were counted in the 1940 Census, including 21 million still alive today. That may include some of your relatives.
Many of these individuals survived the Great Depression and were part of the Greatest Generation, fighting or contributing to the effort during World War II and experiencing new technology, such as the television and microwave.
The census asked a host of new questions for the first time to capture a better picture of families and family life.
Names, addresses, ages and even more personal information like marital status, how many children a family had, how much they earned and what they did for a living were kept under wraps for 72 years — as required by a confidentiality law.
But now the ban has expired and you can get a capsule view of your family. For the first time, the census asked women whether they had been married more than once, their age at their first marriage and the number of children born.
“The release of the 1940 Census releases the actual census form, which is exciting for people like genealogists," said Anne Cahill, Fairfax County's economic, demographic and statistical research manager.
"They can see actually what their family member put on their census forms.”
Here are four tips to help you cruise through history:
1. Where will I be able to research the 1940 census? The National Archives and Records Administration, or NARA, provides free online access to the 1940 census at 1940census.archives.gov. Researchers are able to search the census using NARA's public access computers at any of the agency's archival locations or using any other computer connected to the Internet.
2. There is no name index in the 1940 census. You need to know the enumeration district to find someone. You can locate people by identifying where they lived in 1940 and then browsing the census population schedules for that enumeration district.
The National Archives has placed copies and descriptions of enumeration district maps in NARA's Online Public Access catalog. For more information, visit the 1940 census welcome page.
3. How can I locate someone if I don't know where he or she lived? There are other sources that may provide addresses from around 1940. For more information, go to Start Your 1940 Census Research.
4. The National Archives will certify copies of pages in the 1940 census. Visit the National Archives or send your request to email@example.com. The cost to receive a certified copy by mail is $30.