The United States and China have the two largest and most innovative internet economies, yet there are major differences between their political systems, businesses, foreign policies and approaches to international law. This special issue examines the way the governance of digital platforms characterizes two profoundly different systems of political economy.Some observers believe that the American and Chinese systems of political economy are incompatible, and can only conflict. Deciding whether that belief is true or not requires empirical comparative analysis. Scholars may find as many similarities as differences. When there are notable differences, scholarly research can help reveal why those differences exist and whether they really do lead to conflict.Digital platforms are information services that facilitate value-creating exchanges in what economists call multi-sided markets. In social media, e-commerce, ride sharing and cloud services, they have created large-scale multinational companies such as Google, Amazon, Didi, and Alibaba. Platform governance refers to the laws, regulations, business practices, and design decisions that influence or control platform's content, operations and market access.Typically, academic research in this area consists of Western scholars in the United States and Europe talking about China, or Chinese scholars in China talking about the United States. In an attempt to allow Western and Chinese scholars to conduct objective comparative analysis of each other's digital platform systems and interact with each other, the Georgia Institute of Technology's Internet Governance Project held a conference "Comparative Analysis of Platform Governance in the US and China" in June 2021. The papers published here were selected from that conference.The papers in this special issue cover platform governance from different angles: international trade and security, social media content, competition policy, privacy litigation, and the digitization of money. Trade and international relations are covered by two papers, one by Mueller and Farhat (2022), the other by Cai and Wang (2022). Mueller and Farhat (2022) conduct a sequential analysis of the rise of barriers to United States-China trade in information-communication technology and digital platform markets from 2000 to 2021. They find that both countries are following a policy of digital neo-mercantilism, in which domestic policy makers represent information flows and digital technologies as critical to the security and relative power of the state. As a result, they pursue various forms of industrial policy, data localization, trade protectionism or exclusion of foreigners. Similarly, Cai and Wang (2022) argue that the platform governance strategies of the two countries are actually more similar than they seem. Unlike Mueller and Farhat (2022), however, they view the departure from liberal globalization more positively, as an evolving "middle groas a more pragmatic and balanced approach to the historic turbulence of the United States-China relat...