The concentration of private power over media has been the subject of intense public debate around the world. Critics have long feared waves of mergers creating a handful of large media firms that would hold sway over public opinion and endanger democracy and innovation. But others believe with equal fervor that the Internet and deregulation have opened the media landscape significantly. How concentrated has the American information sector really become? What are the facts about American media ownership? In this contentious environment, the book provides a comprehensive survey of media concentration with a methodical, scientific approach. It assembles a wealth of data from the last twenty-five years about mass media such as radio, television, film, music, and print publishing, as well as the Internet, telecommunications, and media-related information technology. After examining 100 separate media and network industries in detail, the book provides a powerful summary and analysis of concentration trends across industries and major media sectors. It also looks at local media power, vertical concentration, and the changing nature of media ownership through financial institutions and private equity. The results reveal a reality much more complex than the one painted by advocates on either side of the debate. They show a dynamic system that fluctuates around long-term concentration trends driven by changing economics and technology.