Starting out as a Native American path now referred to as the Minsi Trail, this route became part of the Bethlehem Pike. In 1926, the US 309 designation was given to a route that consisted of Stenton Avenue in Philadelphia, Bethlehem Pike (Old Route 309) from the Philadelphia line to Spring House, modern-day PA 309 into Bucks County, Bethlehem Pike (Old Route 309) through Sellersville, modern-day PA 309 from Quakertown to Lanark, and modern-day PA 145 to Allentown; various city streets through Allentown, exiting northward on Walbert Avenue; modern-day PA 309 from Walbert (in South Whitehall Township) to Schnecksville, modern-day PA 873 to Weiders Crossing near Lehigh Gap, modern-day PA 248 to Weissport, modern-day US 209 to Nesquehoning, modern-day PA 93 to Hazleton, and modern-day PA 309 (and PA 309 Business) to Wilkes-Barre.