The vertical production of horizontal capacity: governing transboundary environmental problems in China

China’s environmental governance is commonly understood through the lenses of top-down hierarchy and horizontal coordination. In this article, we challenge their analytical separation by showing that horizontal capacity is not an autonomous counterpart to vertical authority, but a product of it. Drawing on an original dataset of inter-county cooperation (2009–2020) and qualitative fieldwork, we trace how the central state orchestrates interjurisdictional collaboration through mandates, incentives, and institutions. We disaggregate horizontal capacity into relational, accountability, enforcement, and transactional forms, contributing greater clarity to a concept that is frequently invoked but rarely unpacked. Broadly, we show the vertical production of horizontal capacity, where authority is extended not only by directing subnational units, but also by structuring the relations among them. While these arrangements generate new forms of coordination, they remain ad hoc, transactional, and dependent on continued top-down intervention. Horizontal coordination thus produces a system that is more interconnected yet more delicate.