In the summer of 2003, a remarkable cache of recordings came to light in some basement storage bins of an apartment building in Brooklyn, New York. Tucked away in dusty cardboard barrels were dozens of metal masters for recordings dating back to the 1940s – including dozens of numbers, including several unreleased sides, cut by folk music legend Woody Guthrie for the Asch and Stinson labels in the spring of 1944.

The significance of this trove’s discovery cannot really be overstated. Guthrie’s ’44 sessions had for years been available on LP and then CD in dim second-generation copies. Restored and remastered by engineer Doug Pomeroy for Rounder’s four-CD set My Dusty Road, this material is presented for the first time with its original presence and luster intact. Like The Live Wire, 2007’s breathtaking set of live Guthrie recordings from 1949, this new studio collection -- which includes half a dozen previously unheard selections -- is a crucial addition to the singer-songwriter’s library.

Guthrie himself requires little introduction to folk enthusiasts. The Oklahoma-born musician’s homespun, biting, politically brittle compositions and footloose, impish persona had an impact on every folksinger from the ‘40s on, from Pete Seeger and Ramblin’ Jack Elliott to Bob Dylan and a host of ‘60s folk movement acolytes.

His best-known original songs have become the core of the American folk canon, and they are heard anew on “Woody’s ‘Greatest’ Hits,” the first CD in Rounder’s 54-track collection: “This Land is Your Land,” “Going Down the Road,” “Philadelphia Lawyer,” “Pretty Boy Floyd,” etc. The disc also includes a striking newly discovered song, “Bad Repetation” (sic).

The box’s second volume reveals the sources of Guthrie’s music; unsurprisingly, the songs here include a number of energetic Carter Family covers – “Worried Man Blues,” “A Picture From Life’s Other Side,” “Little Darling Pal of Mine,” “Will You Miss Me When I’m Gone” – plus several songs purloined from John A. Lomax’s influential 1910 compilation of cowboy songs.

Disc three is titled “Woody the Agitator,” and takes in the hard political edge of Guthrie’s music. Throughout his career, he donated his time and energy to the causes of organized labor and racial equality, and these performances include a number of sizzling songs about union-busting and Southern injustice, as well as the Left’s ideologically see-sawing take on the Soviet Union’s anti-fascist role during World War II.

During the April-May 1944 recording sessions heard here, Guthrie often performed solo, but on many tracks he was joined in duo and trio numbers by his onetime Merchant Marine shipmate Cisco Houston and the blind singer and harmonica player Sonny Terry. They are heard throughout the compilation, but the fourth CD in My Dusty Road focuses on their contributions, presenting a loose-jointed, jammy package of “the blues, hollers and dances.”

These marvelous performances, in sparkling new transfers from the original metal parts, must really be heard if their full effect is to be appreciated. No less an authority than Nora Guthrie, Woody’s daughter, puts it perfectly in her introduction to the set: “It’s very, very strange. The more time goes by, the clearer Woody’s voice gets.”