The first railroad in the Lehigh Valley began construction in 1851. Shortly thereafter many other railroads entered the Lehigh Valley connecting it to Reading, Philadelphia, Scranton, and Eastern New Jersey as well as serving the developing industries in the valley. By about 1920, new construction had stopped and the railroads operating in the Lehigh Valley had evolved into several competing systems. The Lehigh Valley was utterly dependent upon railroads for most of the past 150 years. Without rail connections industries such as steel and cement, people who worked for them would not have located here.

The single largest change in the structure of the railroads operating in the Lehigh Valley was the creation of Conrail in 1976. Most of the track in the Lehigh Valley were absorbed into Conrail. Over the next ten years Conrail rationalized its physical plant and eliminated much excess and redundant trackage. Since then there has been a resurgence of rail traffic nationwide. As the economy continues to grow and as highways get more crowded, freight is finding its way back to the rails. Many of the abandoned rail lines have found a second use as multi-use trails. Where locomotives once labored, bikers and hikers now enjoy the countryside. 

For this LEO project graduate and undergraduate students worked together with faculty from many departments in organizing a database of population and transportation infrastructure in the Lehigh Valley. ArcView was used to create maps showing the growth and decline of railroads in the region. This data should serve as an important archive of information for everyone from historians to transportation planners.