Years into the single currency, EMU financial markets are not fully integrated. We argue that the phenomenon can be better understood by looking at financial markets' behavior in the wake of Italy's monetary unification (1862). Variables such as the spread of the telegraph, trade volumes, and the diffusion of the 'single currency' fail to explain why it took 25 years for prices across regional stock exchanges to converge. A single Italian financial market appeared only when the State prevailed upon local vested interests by enforcing nation-wide financial market legislation. © 2003 Elsevier Inc. All rights reserved.