The newly released 1940 U.S. census is such a digital smash that it took a day for the website hosting it to get up to speed after tens of millions of hits almost paralyzed it.
The National Archives said Tuesday that census pages are again available for viewing. The government website got 37 million hits hours after the information was first released to the public Monday morning, all but shutting out would-be researchers from the records.
"We expected a flood, and we got a tsunami," Archives.com, the private company that's hosting the website, said in a statement.
The government released the 1940 census records _ the single largest collection of digital information ever made available online by the National Archives _ for the first time after 72 years of confidentiality expired. The records allow individuals and families to learn details about their pasts.
Documents obtained by The Associated Press show the National Archives badly underestimated their popularity. The no-cost contract awarded in November to the third-party Web host required that the site be able to handle up to 10 million hits per day and up to 25,000 concurrent users. The documents also said the site was expected to scale up to handle greater demand.
In another document issued in early 2011 that explained why the National Archives wanted to contract hosting of the records, the archives said its own site could handle only between 250 and 500 concurrent users.
In a tweet posted after 5 p.m. Monday on its Twitter account, the archives said the website had gotten 37 million hits since the information was released at 9 a.m. A spokesman for the company hosting the records said they were receiving even more traffic Tuesday as interest in the 1940 census continued to grow.
Joe Godfrey, the senior director of projects for Archives.com, said he didn't immediately have updated information on how many hits they had received but said it was expected to exceed Monday's.
Susan Cooper, an archives spokeswoman, said the problems began as soon as the information was released on the website. She termed the problems a "virtual traffic jam."
"The problem is, we just weren't expecting the huge volume that we got," Cooper said.
"We're adding a lot more servers, a lot more muscle to the website," she said.
Godfrey said Tuesday that the company's engineers spent the good part of Monday into the evening working to expand the company's ability to handle the unexpected crush of traffic. He said the company had tested the site based on receiving 75,000 to 100,000 concurrent users.
He said that in the hours after the records' release Monday, they were "reaching well into the six figures in concurrent users," but he didn't have a number.
"It exceeded our most optimistic estimates," he said.
Bob Timmermann, a 46-year-old librarian from Tujunga, Calif., said the lure of the 1940 census is that "you find out if what your parents told you about their lives was actually true."
He said he had tried for several hours Monday to access data but was unsuccessful.
More than 21 million people still alive in the U.S. and Puerto Rico were counted in the 1940 census. The census followed a decade in which tens of millions of people in the U.S. experienced mass unemployment and social upheaval as the nation clawed its way out of the Great Depression and rumblings of global war were heard from abroad.
Monday's release includes digitized records for details on 132 million people. Access to the records is free and open to anyone online, but they are not yet searchable by name.
For now, researchers will need an address to determine a census enumeration district _ a way to carve up the map for surveying _ to identify where someone lived and then browse the records.
Every decade since 1942, the National Archives has made available records from past censuses. The records, which include names, addresses and income and employment information, are rich with long-veiled personal details.
Associated Press writer Whitney Phillips in Phoenix contributed to this report.