Several of the papers in this volume are concerned with assessing both the timing and the impacts of deregulation and regulatory reform in the US transportation sector. Of increasing interest is the importance of productivity growth and the role played by new technologies in a more competitive market environment. Four of the papers in this volume deal directly with these issues in the context of motor carriers and railroads, two sectors which have been operating under substantially reduced regulatory constraints for the past twenty years in the US. Although the financial condition of US railroads has improved since 1980, there is still some concern regarding their long run viability as private enterprises. Accordingly, one of the papers considers the potential for further reductions in railroad costs through transcontinental mergers, a controversial issue due to the small number of railroads that remain in the industry.