For one thing, costs are prohibitive. Scanning alone on smaller items ranges from $6 to $9 for a 35-millimeter slide, to $7 to $11 a page for presidential papers, to $12 to $25 for poster-size pieces. (The cost of scanning an object can be a relatively minor part of the entire expense of digitizing and making an item accessible online.)
But the reality remains that a new generation of researchers prefers to seek information online, a trend made all too clear to Mr. Hastings of the National Archives last year, after Google, in an experiment of sorts, digitized 101 of the National Archives' films — including World War II newsreels and NASA footage — and put them up on its site, at video.google.com/nara.html.
"Before that happened, we had 200 requests total for the whole year in our research room," Mr. Hastings said. "The first month the films were available on Google, there were about 200,000 hits on them — a thousandfold increase."...
WHILE copyright is not a concern for those digitizing documents that are hundreds of years old, copyright restrictions play a significant role when it comes to modern material. Even if the Steinbeck Center in Salinas were to find the money to digitize, say, the manuscript of "The Pearl," its copyright would limit its distribution.
"At this point, online materials are best for authors no longer under copyright," said Susan Shillinglaw, a professor of English at San Jose State University and scholar in residence at the Steinbeck Center.
When Leonard Bernstein's family donated the composer's papers to the Library of Congress in 1993, it was with the goal of digitizing portions of the collection and making them broadly accessible. Although more than a thousand items from the collection have been digitized and placed on the library's Web site, there is still an enormous quantity of material that, because of sheer volume and copyright concerns, is still accessible only to researchers who travel to the library.
For instance, the collection includes a seven-page letter that Jacqueline Kennedy wrote by hand to Bernstein at 4 a.m. on June 8, 1968, the day after the funeral for Robert F. Kennedy, thanking him for conducting Mahler's Requiem during the ceremony. The letter is an extraordinary window into her grief: "Your music was everything in my heart, of peace and pain and such drowning beauty," she wrote. But the library would need permission from the estate of Mrs. Onassis to digitize it.
When it comes to sound recordings, copyright law can introduce additional complications. Recordings made before 1972 are protected under state rather than federal laws, and under a provision of the 1976 Copyright Act, may be entitled to protection under state law until 2067. Also, an additional copyright restriction often applies to the underlying musical composition.
A study published in 2005 by the Library of Congress and the Council on Library and Information Resources found that some 84 percent of historical sound recordings spanning jazz, blues, gospel, country and classical music in the United States, and made from 1890 to 1964, have become virtually inaccessible.
"Copyright is a very blunt instrument," said Tim Brooks, the author of "Lost Sounds: Blacks and the Birth of the Recording Industry, 1890 to 1919" (University of Illinois, 2004). "Once you have copyright, you have total control; there's very little room in the copyright law even for preservation, much less reissuing material."
Generally, rights owners like Sony BMG have reissued on CD only a small portion of the recordings they control.
For example, John Philip Sousa's own band made scores of recordings for Victor Records in the early 20th century. BMG bought Victor in 1986, and few if any of those recordings have since been reissued on CD. "There is probably an odd track out somewhere," Mr. Brooks said, "but they've certainly never done any kind of retrospective of him that I'm aware of." And of the hundreds of recordings made in the same period by Noble Sissle, an African-American tenor who recorded for several labels now owned by Sony BMG, few if any have made it onto CD.
THE result, Mr. Brooks said, is a series of gaps in the popular understanding of the nation's musical heritage. "It's as if before Bessie Smith, there was nothing," he said. "It has the effect of narrowing our own understanding of our own history."
Another factor that determines what is digitized is how straightforward it is to copy the material.
In some cases, said Theresa Salazar, curator of Western Americana at the Bancroft Library at the University of California, Berkeley, the two go hand in hand. "Agencies and organizations providing funding often want large volume for their money," Ms. Salazar said.
For example, she pointed out, objects like books can be handled in a straightforward way. It is easy to capture these materials because they are printed, and many of these titles are more or less the same size.
No one knows this better than Google, whose digitization efforts focus mainly on books.
In its quest to scan every one of the tens of millions of books ever published, Google has already digitized one million volumes. Google refuses to say how much it has spent on the venture so far, but outside experts estimate the figure at at least $5 million. The company has also been scanning and indexing academic journals to make them searchable, and is working with the Patent Office to digitize thousands of patents dating back to 1790.
David Eun, Google's vice president for content partnerships, said that rather than dwell on what is being left behind, he preferred to take a more optimistic view.
"We're talking about a huge, huge universe of content," Mr. Eun said. "If you look at the glass as half-empty it becomes too overwhelming."