This paper describes a system developed by the Idaho Transportation Department (ITD) and DKS Associates to produce visual displays of how growth in the key rural corridors in eastern Idaho will affect the health of state facilities and how investments can reduce the long-term impacts of that growth. The system includes a geographic information system (GIS) as the base platform where a variety of data on roadway characteristics, land use, population and employment forecasts, and traffic counts are stored and organized. The system also includes a module for producing travel forecasts from population and employment growth forecasts and from historical trends in growth in traffic volumes to reflect growth in the corridor and growth in recreational travel to the region. For a future scenario, the GIS program generates a graphic display of the level of service for different times of the day, days of the week, and seasons of the year. It also can generate a graphic display of the health of the corridor where "health" is defined by a set of factors and criteria that describe how the corridor would be perceived by travelers who use it and how the roadway facility affects the economic health of the corridor. The visualization tool has been successfully used by ITD to help the counties in eastern Idaho develop plans that anticipate and acknowledge the growth and other changes in the critical state route corridors.