The state made the system and the system made the state

State systems vary in terms of the importance of declaratory versus constitutive forms of establishing statehood. We argue that interaction capacity explains this variance. Thinly developed systems with lower interaction capacity exhibit more declaratory properties of statehood, where states have less need to seek acceptance into an institutionalized “club” of states. Conversely, in systems with higher levels of interaction capacity, constitutive forms of recognition are more pronounced. Based on a combination of a qualitative analysis of historical state systems and a longitudinal network analysis of the contemporary international system, we demonstrate that increasing interaction capacity shifts the organizational principles of state systems from declaratory to constitutive practices. We theorize that this is how systems evolve. In thinner, low-capacity systems, states come first and make the system. But as the system thickens and constitutive practices are developed to manage crowding, it gradually determines who can be a state. Over the long run, the state made the system and the system made the state.