This dissertation examines how the Internet is altering the flow of political information in the United States. It hypothesizes that the Internet is shifting communication from a "broadcast structure," where information flows unidirectionally from organizations to the public via intermediaries like the press, to a "netcast structure" with an omnidirectional flow that bypasses intermediaries. Case studies and an online survey are used to test the hypothesis and 10 effects on political agents and participation. The findings contribute to literature on political communication, diffusion of information, and information flow within governments and political systems.