In his almost 40 years of active field recording, Alan Lomax was a tenacious, even obsessive, documenter of folk music and the stories of the people who performed it. He judged, quite rightly, that what he missed would likely be lost to history altogether, so he tried not to miss a thing. He was so thorough and prolific that it has become the absorbing work of his daughter, Anna Lomax Wood, and the Lomax Archive just to unpack, organize, preserve, and promote all that he managed to capture.

A steady stream of material has sprung from the archive over the years, most substantially from the Rounder Records “Alan Lomax Collection” CD series that now numbers almost 90 discs. But so vast is the archive of material that this is like trying to pass an ocean through a garden hose. Starting this week, however, the public can finally glimpse the scope of Lomax’s work with the publication of the Lomax Archive Database (available at the Web site www.lomaxarchive.com), a multimedia catalog of audio and video recordings and photographs – searchable by performer, song title, geography, culture, genre, subject, instrument, collection, session, and date – that spans the years 1946-94.

Before proceeding to gush, let me first offer a couple of quibbles and qualifiers. First, it should be pointed out that the database includes only 40-second snippets of each audio track. (Where commercial recordings are available, the database links to iTunes, but this is only the case for a fraction of the material.) This is an understandable concession to the sheer magnitude of the collection, but also a highly annoying one. While 40 seconds gives you the flavor of a three-minute song, when it comes to interview tracks – some of which stretch to 20 and 30 minutes in length – it is almost completely useless. Go through this exercise enough times, and it begins to feel like folk music’s answer to the peep show: Just as your interest is aroused, the window of history slams shut.

Also significant is the absence of the work Lomax recorded under the auspices of the Library of Congress between 1933 and 1946. This means no Leadbelly, no Woody Guthrie, no Muddy Waters, and no Jelly Roll Morton – all the names with which Lomax is most often associated. The reason for this cleavage in his career is that, by the mid-1940s, Lomax found his project and politics – which might be characterized by Guthrie’s quip: “I ain’t no Communist necessarily, but I been in the red all my life” – at odds with the prevailing climate in Washington. He left the Library of Congress in 1946, and left the country for Britain in 1950.

The online database focuses on his post-1946 work, which – though less star-studded – is equally rich. After 1946, Lomax worked as a folk-hunting free agent, producing regional collections for a variety of labels and broad casters, including Atlantic Records and the BBC. The first installment of the Lomax Archive Database includes material drawn from six collections made during this time: a 1946 concert of Trinidadian Calypso music, recordings of Virginia ballad singer Texas Gladden, also from 1946; Mississippi prison songs recorded in 1947 and 1948; a 1952 Paris interview with Chicago bluesman Big Bill Broonzy; a pre-Newport Folk Festival concert Lomax organized in Central Park in 1965; and, most significantly, recordings from the trip he made with English folksinger Shirley Collins through the American Southeast in 1959 and 1960.

Just back from Europe, Lomax saw America’s native folk traditions with fresh eyes and the need to preserve them with renewed urgency. The trip produced the first recordings of the now-legendary blues singer Mississippi Fred McDowell, as well as sessions with prison work gangs, fife and drum bands, sacred harp singers, and church choirs, black and white – all musical styles that were on the verge of obsolescence.

This trip has been well examined already. It is the subject of a 13-volume “Southern Journey” series on Rounder Records, and also an emotional memoir by Collins (who was Lomax’s assistant during part of the trip, and his lover). What the Lomax Archive Database does, however, is present in full the sweep of the endeavor, the richness of the content, and the breadth of Lomax’s definition of what defines culture and is worthy of preservation.

The most interesting stuff is also the least familiar: all the interviews and odds and ends that fall between the cracks of the formal recording dates. Driving from Scottsboro to Huntsville, Ala., for instance, Lomax recorded a country preacher delivering a daylong sermon on the radio in the flat, shrill voice of a cattle auctioneer. A little later, on the same road, he captured a fast-talking DJ named Daddy Cool as he read a news wire about the American-Soviet space race in a staid monotone, then launched into a jive-riddled dedication of a record. (“Yessir daddyos and mommy-os, let’s get back on the scene, I hope you all get what I mean, out there shoot-the-toot, toot-a-loot, but just don’ over lovur.”).

Lomax found this kind of color at every turn. In Mississippi, he recorded a hitchhiker’s convoluted rambles about white supremacy, angels (he claims to have seen 33), and the government. In Whitesburg, Ky., he talked with an old banjo-picker named Ada Combs – who speaks in a gummy mouthed brogue – about snake handlers, courtship at corn-shuckin’s, and shooting her husband’s mistress with a gun. These are documents of an America that still existed only 45 years ago, but was much older.

The pairing of photos with sounds on the Web site enriches the experience considerably. Lomax had an eye, as he had an ear, for iconic moments and deeply personal ones. Thus a series of shots taken at Parchman Farm Penitentiary in Mississippi ranges from inmates sweatily chopping wood in the field to inmates dressed in button-up shirts and ties (an odd pairing with their prison-striped pants) to receive visiting girlfriends and wives in the dining hall. Couples dance between tables and pose for the camera as if they were at a prom. Look at these pictures, then listen to Ervin Webb’s mournful prison song “I’m Going Home” from the same date, and you begin to get a sense for where the tragedy in his voice comes from.

There is irony, in this melding of the new and old, of an Internet database and field recordings, and it’s a testament to the potency of the material that it maintains its power to move you in a context such as this. Lomax viewed technology as both friend and foe. The same recording advances that enabled him to preserve local music traditions also hastened their decline with the spread of pop records and radio.

It was, Lomax knew, a race against time – one he would eventually lose. Today, many of the traditions he raced to capture now exist only in his collections. It’s only right that technology should now work on their behalf.