Rogers found a substantial decline in the dispersion of traded-goods prices across European cities over 1990-2001. Indeed, by the end of the period, the variability of traded goods prices across cities within EMU countries had declined by more than half, and it was not substantially different from the variability found among cities in the United States.
This convergence of prices suggests a powerful, ongoing process of increased economic integration and elimination of barriers to trade among the members of the European Monetary Union. Crucially, however, Rogers found that the bulk of this convergence occurred between 1990 and 1994, the period of the “single market” initiative.