Main Line (Pennsylvania)

Main Line of Philadelphia Mainline, Main Line, Philadelphia Main Line
Collection of suburban communities
Map of the historic Main Line, circa 1895.
Location of Pennsylvania in the United States
Country	United States
State	Pennsylvania
County	Delaware, Montgomery, Chester
Named for	The Pennsylvania Railroad's Main Line
Demonym(s)	Main Liner
Time zone	EST (UTC-5)
• Summer (DST)	EDT (UTC-4)
Area code(s)	610, 484, 267, 215

The Philadelphia Main Line, known simply as the Main Line, is an informally delineated historical and social region of suburban Philadelphia, Pennsylvania. Lying along the former Pennsylvania Railroad's once prestigious Main Line, it runs northwest from Center City Philadelphia parallel to Lancaster Avenue (U.S. Route 30).

The railroad first connected the Main Line towns in the 19th century. They became home to sprawling country estates belonging to Philadelphia's wealthiest families, and over the decades became a bastion of "old money". Today, the Main Line includes some of the wealthiest communities in the country, including Lower Merion Township,Radnor Township,Gladwyne, and Villanova. Today, the railroad is Amtrak's Keystone Corridor, along which SEPTA's Paoli/Thorndale Line operates.

The Main Line region was long part of Lenapehoking, the homeland of the matrilineal Lenni Lenape Native Americans (the "true people", or "Delaware Indians"). Europeans arrived in the 1600s, after William Penn sold a tract of land, called the Welsh Tract, to a group of Welsh Quakers in London in 1681. This accounts for the many Welsh place names in the area.