This chapter presents the book’s macrolevel findings about the architecture of political communication and the news media ecosystem in the United States from 2015 to 2018. Two million stories published during the 2016 presidential election campaign are analyzed, along with another 1.9 million stories about Donald Trump’s presidency during his first year. The chapter examines patterns of interlinking between online media sources to understand the relations of authority and credibility among publishers, as well as the media sharing practices of Twitter and Facebook users to elucidate social media attention patterns. The data and mapping reveal not only a profoundly polarized media landscape but stark asymmetry: the right is more insular, skewed towards the extreme, and set apart from the more integrated media ecosystem of the center, center-left, and left.