The book examines US states’ and cities’ paradiplomacy—subnational engagement in foreign relations—towards China and Taiwan from 1949 to 2020. As an alternative diplomatic history of the United States’ relations with divided China, it offers an in-depth chronological and thematic discussion of state and local communities’ responses to the China-Taiwan sovereignty conflict and their impact on US diplomacy. The book explains why paradiplomacy matters not only in the ‘low politics’ of economic and cultural cooperation, but also in the ‘high politics’ of diplomatic recognition. It presents numerous case studies of US states and cities developing policies towards divided China that paralleled, clashed or aligned with those pursued by federal agencies. It also identifies Chinese and Taiwanese objectives and strategies deployed when competing for US subnational ties. Conceptually, the book builds upon Constructivism, redefining paradiplomacy as an institutional fact, reflective of subnational identities and interests, rather than as a subnational pursuit of foreign markets, driven by objective economic forces. Featuring new empirical evidence and a novel conceptual framework for paradiplomacy, The United States’ Subnational Relations with Divided China will be useful for students of US foreign policy, China and Taiwan studies, paradiplomacy and international relations.