In 1828, the Pennsylvania legislature authorized the construction of the railroad between Philadelphia and Pittsburgh. This was known as the "Main Line" of the Public Works system. This, in turn, caused the development of the surrounding area.
After the Civil War, track improvements were sought and new station houses were erected to include more stops along the line. In recognition of the heritage of the areas along the rail line, many stations were given English and Welsh names, such as Narberth, Ardmore and Bryn Mawr.
Many changes were made to the rail route and so the Commonwealth purchased lots surrounding the rail line with stipulations on setbacks and improvements to the land next to the station houses. In Bryn Mawr, it stated that the building of "hotels, taverns, drinking saloons, blacksmiths, carpenter or wheelwright shops, steam mills, tanneries, slaughterhouses, skindressing establishments, livery stables, glue, candle or starch manufactories, or other buildings of offensive occupation" was prohibited.
The result was "a complete picture of suburban comfort and elegance with wide avenues and roomy and open ornamental grounds, spacious lots for building and homes of more than ordinary architectural tastes." These new homes served as the summer residences for many affluent families. The Main Line was now established. The Pennsylvania Railroad promoted this area in brochures describing the "opportunities provided by the railroad for 'summer sojourns' away from the city and the desirability and convenience of suburban living."
The success of the Bryn Mawr development encouraged A.J. Drexel and George Childs to build the area surrounding the Wayne Train Station. Over the next decade, 150 new homes were built. This planned community had its own electric system and "was the second town in America to have electricity in every home."
The Devon area was next. A large hotel—the Devon Inn—was constructed to attract summer visitors. Developers Lemuel Coffin and Joseph B. Altemus purchased the land and wanted to build on the success of the previously built Resort Hotel in Bryn Mawr (now the Baldwin School).
From the 1880's to the 1890's, improvements were made to the highway between Philadelphia and Paoli. This was known as Lancaster Avenue. This would add to the accessibility and convenience of the Main Line area. New schools were built, libraries, places of worship and fire and police departments were established to accommodate the growing population. The original farmlands were now transformed into the prestigious Main Line.