Until 1972, sound recordings were not protected by federal copyright law in the United States. In the years following the invention of the phonograph in 1877, Americans searched for the right legal, economic, and ethical principles to govern the reproduction of recordings. Practices ranging from tape-trading to commercial piracy raised difficult issues about the ownership of creative expression and the value of entertainment to the national economy. This study traces the development of recorded sound as a form of property, from debates in the Progressive Era about copyright as a monopoly to the emergence of a powerful political discourse that favored "intellectual property" in the late twentieth century. It shows how Americans gradually perceived a distinctive value in recorded performances, which lawmakers and judges had initially treated as merely "mechanical" representations of written music. It argues that record collectors, beginning in the 1930s, drew attention to this value by trading and selling copies of discs that major labels had let fall out of print. Aficionados of other genres, such as opera and blues, carried on copying and exchanging rare recordings in the ensuing decades, using new media to capture sounds from radio broadcasts and concert performances. Such activities went largely unnoticed for years. However, the political dynamics of piracy changed dramatically when Earl Muntz and other entrepreneurs reengineered magnetic tape as a cheaper, mobile technology in the 1960s, and bootlegging of popular artists such as Bob Dylan and the Beatles became entwined with youth culture and radical politics. Drawing on court and legislative records, industry journals, fan media, and oral history, "Music Piracy and the Value of Sound" examines a sea change in the way Americans understood the relationship between creativity, property, and economic production. It shows how the record industry's successful campaign for copyright protection inaugurated an era in which further reforms expanded the power of intellectual property rights to an unprecedented degree. However, the development of new patterns of free exchange in the remaining decades of the twentieth century suggested that stronger copyright restrictions alone could not prevent the unauthorized reproduction of recorded sound.