Tzeachten Gas Bar, 6336 Vedder Rd, Chilliwack, BC, Canada. Still exists. In Google StreetView you can even pan/zoom (looking east-southeast from that address) and see the exact same blurry ridgeline.
Roughly 50 miles east of Vancouver and 2 miles south of the Trans-Canada Highway 1.
@1, I have no specific knowledge other than seeing my childhood construction-paper artworks fade on the family fridge, but I think it would involve contact "printing" with a positive transparency on the black construction paper, exposed to daylight or UV, because light areas like sky would be nearly clear on the positive transparency and transmit more light-->more fading of the black paper.
I am interested in the process
Roughly 50 miles east of Vancouver and 2 miles south of the Trans-Canada Highway 1.
http://www.uslces.org/gas_stations.htm