FRANKFORT — Kentuckians have more to gain by surfing the 1940 census than finding the real age of country icon and noted coal miner's daughter Loretta Lynn.

Seventy-two years after census workers went house to house and filled in ledgers by hand, the 1940 U.S. Census was released. Why 72 years? Because at the time that number of years was thought to be longer than most life spans, according to the Census Bureau, and hence preserved confidentiality.

The 1940 census is important because it was effectively a census of both 1935 and 1940 and reflected the federal government's desire to know how the population had dispersed and reordered itself during the Great Depression, said Louise Jones, director of special collections and library for the Kentucky Historical Society.

Also, it's a valuable tool for the millions of Americans interested in genealogy and family research.

The disparity in Lynn's age made national news in May when The Associated Press found that in the 1940 census Melvin Webb lists his daughter "Loretta" as 7 years old. Lynn's marriage license, obtained by the AP from the Johnson County clerk's office, lists her as 15 on Jan. 10, 1948. Lynn had always professed to having been a 13-year-old bride.

Perhaps a little less worthy of national news, Jones recently found the record of two Perry County families who had no fixed address and were in fact living in the woods at the time of the census. She gives credit to the census taker for figuring out that not everyone was housed.

All the 1940 information — collected by tromping from house to house and written by hand by the census workers, called "enumerators" — is in databases photographed in its original form. It includes many different handwriting styles in a pre-Internet era when no matter how standardized the questions seemed, many different interpretations were possible.

It has to be logged into a computer database and then checked for accuracy to make it easy for the millions of searches it will draw.

The information became available in April for volunteers across the country to put into a searchable format. Kentucky anticipates getting its searchable census information completed in about another month. Thirteen organizations across the state are helping to input the data.

One Knott County teacher, while typing in data, was delighted to discover her grandmother's records, Jones said.

Some items in the census have to be taken in their historical context, Jones noted. The term then used for blacks was Negroes, a term that made Jones pause as she initially dealt with it.

Other changes in the way we live are more subtly documented. For example, Jones discovered that her two-bedroom, one-bath Frankfort home housed seven people back then. And "Fairy" was apparently a common girl's name, mercilessly garbled in its spelling.

For the 1940 census, a few participants were asked additional questions about their parents and their Social Security status — whether they had a Social Security number and were making payments into Social Security, which had only been established in 1935.

"It isn't really until Social Security comes in that you get the regimented spelling," Jones said. "At the time people are like, 'My name's Hobart. I spell it this way, and I have something over here that spells it with a 'u.'"

The census information completion rate varies by state.

Phyllis Spiker, the genealogy and family history leader for the Central Kentucky Computer Society in Lexington, said that census data will be available and free on the major genealogy Web sites, including Ancestry.com and Familysearch.org. But there are tricks to learn to tease out the data you want.

First is the pesky "enumeration district." If you can find the sometimes-elusive enumeration district number for your family in the 1930s census — which is available now — you can make a pretty good guess about where they are in the 1940 census.

Still, finding that number can take a bit of searching because basic searches of census data include some errors such as erroneous spellings of first and last names. Spiker sails around such errors like a pro and describes the search as a sort of competition with the data: "One of the games we play is, is it the same person aging? Is it a new wife? ... All records lead to another. You have to make sure you have a name connecting."

Census data was never intended for genealogy research, she said. Only more recently have people begun to realize that such data is of interest to individual citizens as well as government officials and trend-spotters. Savvy researchers can use records such as Civil War rosters and railroad pension information to track their ancestors, Spiker said.

And what about the 2010 census, you ask? Expect it to be released in 2082.

Cheryl Truman: (859) 231-3202. Twitter: @CherylTruman