In the middle of bluegrass and bourbon country in Harrodsburg, Kentucky, is Corning's oldest glass factory. It was built in the 1950s to create lenses for glasses, then transitioned into making LCD glass panels in the 1980s.

About six months before the first iPhone was released in 2007, Steve Jobs made a call to the CEO of Corning and asked the company to create glass that could withstand scratches and breakage for a new Apple product. Before that, phones were typically covered in plastic. Corning quickly developed Gorilla Glass and the factory went through a complete transformation.

The same company that developed the glass for the Edison bulb in 1879 is now making the glass that covers 6 billion smartphones, tablets, screens and wearables worldwide for Apple, Samsung, LG, Sony, Huawei and a variety of other manufacturers.

Here's a rare look inside the factory where Gorilla Glass is made.