Alternative hypotheses of market integration in the U.S. winter market for fresh tomatoes were evaluated using a dynamic model of spatial price adjustment. The results showed that while Florida and Mexico were integrated in the same market, a price change in one area was not instantaneously reflected in the other. Lagged effects were important with long-run integration being supported for both Florida and Mexico and short-run integration for Mexico. However, the information flow, while relatively efficient, was not symmetric. Florida was found to be dominant in the price formation process with Mexico responding to changes in the Florida price.