The European Union is the oldest and most highly developed example of institutionalized regional integration. Since its establishment in the early 1950s, the EU has moved from the shallow integration of dismantling trade barriers to the deep integration of accepting common policies on agriculture, environment, transport, and working conditions; common rules on competition, mergers, and financial transfers; and common laws in the domestic courts of member states.

The EU experience is a successful example of integrating national economies, but how far should those promoting regional...