By Emanuella Grinberg, CNN
(CNN) - Personal, historic details of more than 132 million people were released online through the 1940 Census Monday, providing the public with free access to a slice of American history.
Earlier Census records were made available to the public, but not all of them are searchable online free of charge, said Megan Smolenyak, family history advisor at Archives.com. Monday's release marks the first time researchers, genealogists and history hunters can find detailed records online in one place for free.
The 1940 Census was conducted as the Great Depression was winding down and before the country’s entry into World War II, reflecting the economic tumult of the era and the New Deal recovery program of the 1930s.
"The 1940 set is really special because of the time it captures, which was so pivotal in American history," Smolenyak said. "It's not only for people seeking information about their families; for people 72 and older it provides a snapshot into their early lives."
In an era when households consisted of multiple generations of families, the records include names, ages and occupations of everyone in the home, she said. The 1940 Census also marked the first time people were asked detailed questions about their homes and whether they had a radio, “flush toilets,” electricity or running water.
For now, the site is not searchable by names. Starting a search requires an approximate address from April 1, 1940, to find the right “enumeration district,” or geographic area covered by a census taker. (Address sources could include birth, marriage and death certificates, employment records, scrapbooks, Social Security application information or the 1930 census.)
The enumeration district can then be plugged that into a search engine to browse Census records from that area.
In an era before mail-order surveys and online questionnaires, census workers went door-to-door to collect information. Questions new to the census included residence five years earlier, income, highest level of school completed and detailed questions on unemployment history, meant to measure the effects of the Great Depression.
The records reveal a snapshot of history.
Occupations listed as examples for the occupation question included frame spinner, salesman, laborer, rivet heater and music teacher. Examples of industries included cotton mill, retail grocery, farm, shipyard and public school. The 1940 Census counted 5.1 million farmers, compared with 613,000 farmers, ranchers and other agricultural managers tallied in the 2010 American Community Survey.
In 1940, a supplementary census asked veterans if they served in the World War, Spanish-American War, Philippine Insurrection or Boxer Rebellion. The supplemental schedule also asked about participation in two national insurance plans: Social Security and Railroad Retirement.
Monday's release shows more details about the 1940 Census data, which was already searchable online, and shows how much the country's population and demographics have changed.
The country's population grew from 132 million in 1940 to about 308 million in 2010. New York was the most populous state in 1940 with 13.5 million people; during the most recent census in 2010, California earned the top spot, with 37.3 million people. New York City, the country's most populous city, had 7.3 million people in 1940, compared with 8.2 million people today.
The 1940 Census also found that 89.8% of the population was white and 9.8% was "Negro." Other options for race included Indian, Chinese, Japanese, Filipino, Hindu and Korean - the 1940 Census didn't collect information on the Hispanic population.
The 2010 Census found that 72.4% and 12.6% of the U.S. population was single-race white and black, respectively, and that 4.8% were Asian, 0.9% were American Indian or Alaska Native and 2.9% were two or more races. In 2010, 16.3% of the population identified as Hispanic, which can be any race.