Sierra Designs

What is now acknowledged as the first parka to carry the name "60/40" was originated by Bob Swanson and George Marks of Californian brand Sierra Designs in 1968. 

Swanson had learned his trade with the likes of Holubar Mountaineering in Colorado and Trailwise in Berkeley, California. Marks meanwhile had proper scientific credentials having shivered his way through a stint in the Antarctic for the National Science Foundation.
 
They opened Sierra Designs in the winter of 1965. In keeping with much of the outdoor garb that came out of that area around the late 60s and early 70s, the 60/40 mountain parka was born out of necessity and innovation. With gore-tex a decade away from being developed, there was no clear material that did the job as well as the one Sierra Designs put together. Wind-proof, water-repellent, durable and with enough pocket space to rival a modest day pack the 60/40 parka soon became the perfect choice for backpackers in the USA and still enjoys unrivalled popularity today.