Book excerpt: In the 1920s, as radio took over the pop music business, record companies were forced to leave their studios in major cities in search of new styles and markets. The recordings they made of the ethnic groups of America helped democratize the nation and gave a voice to all its people: a woman picking cotton in Mississippi, a coal miner in Virginia, or a tobacco farmer in Tennessee could have his or her thoughts and feelings heard on records played in living rooms across the country. These records blended the intertwining strands of Europe, Africa, the Pacific Islands, and the Americas and formed the bedrock for modern music as we know it. Today, virtually no documentation of these extraordinary events survives, and nearly 90 percent of the music masters have been destroyed. Bernard MacMahon and Allison McGourty spent years traveling around the U.S. on a mission to rescue this history, interviewing hundreds of families and scouring attics and basements, collecting vintage film footage and hundreds of photographs that haven't been seen in nearly a century. This written account continues the journey of the PBS television series and features additional stories, photographs, and artwork. It also contains contributions from many of the musicians who participated, including Taj Mahal, Nas, Willie Nelson, and Steve Martin, plus a behind-the-scenes look at the incredible adventure across America in search of these recordings and eyewitness accounts.