The populated area today known as Hillsdale took form in the mid-to-late 19th century as land speculators, led by David P. Patterson, developed subdivisons to profit from the coming of the Hackensack and New York Railroad (later New Jersey and New York Railroad).
Gap is a census-designated place and town in Salisbury Township, Lancaster County, Pennsylvania with a zip code of 17527. The population was 1,611 at the 2000 census. It is the terminus for four Pennsylvania highways: 772, 741, 897, and the heavily-used 41, which goes toward Wilmington, DE. Gap has a history which can be dated as far back as William Penn's first visits to the area.
The Big Stone Gap refers to the valley which has been created on the Appalachia Straight, located between Big Stone Gap and Appalachia. The town had hoped that its coal and iron ore deposits would make it the Pittsburgh of the South. The Big Stone Gap post office was established in 1856.