Railroad network rationalization constitutes a process of adjusting the size and configuration of the railroad plant and its utilization in conformity with current and prospective volumes of traffic to obtain optimum efficiency in costs and levels of service. This report reviews the nature and scope of prior efforts to rationalize rail networks, including the Transportation Act of 1920, the Emergency Transportation Act of 1933, abandonments, mergers, and rail-highway coordination. It has been found that, in most respects, these prior schemes have either failed entirely or have achieved less than their anticipated success. Numerous opportunities for improving industry performance have been hampered by interfirm rivalries, managerial insensitivity, employee organizations' opposition, and regulatory constraints imposed by statute or by directive. A recognition both of these restraining factors and of the potential benefits should advance the rationalization process in the future.