What happens to subnational states when the federation to which they belong begins to undergo regime change? In an authoritarian system, the federation monopolizes political initiatives, including the initial move toward transition. However, regional actors profoundly transform federal processes by giving them a resolutely subnational logic. Regional institutions, identities, and history are therefore transformed into frontiers between the regions and external processes. As a result, the reiteration of this mechanism throughout the democratic transition process produces new, separate regional political systems. This mechanism is illustrated here through a comparison of three Mexican States: Guanajuato, San Luis Potos?, and Zacatecas.