Ahem: "Fifty years ago — on Jan. 11, 1971 — journalist Don Hoefler started a three-part series in Electronic News about the Bay Area semiconductor industry titled 'Silicon Valley U.S.A.'" Hoefler hadn't invented the name, but this was the first time it was used in print.
It took a while to propagate. I'd already been living in Silicon Valley for a decade at the time, but it took yet another decade before I heard the name, though by then I was already well aware of its manifestations. I knew people who were early employees at Apple, for instance, because they were also science-fiction fans as I was. But though I'm electronically enhanced in a way - I'm the librarian who took away your card catalog and replaced it with a computer database, literally so in the case of a couple local colleges - I've never worked for a tech firm, though I had a narrow escape or two.
The linked article says that Silicon Valley is now so famous that people know where it is who couldn't find San Jose, the largest city in the area, on a map. I'm not so sure about that, or at least that it's always been this way. Silicon Valley was already as famous, and not nearly so tattered in reputation, in the mid 1990s as it is today, and that's when I was visiting a Brit who, on my mentioning an association with the place, hauled out an atlas and asked me to point out exactly where Silicon Valley was, anyway.
I defined it, at least then, as a concept rather than a place, but it did have a geographical location, and I identified that as the contiguous area where electronics seemed to be the principal industry: centered on the area just west/northwest of San Jose (Santa Clara, Sunnyvale, Mountain View, Cupertino) and radiating as far NW as Redwood City, to the north to Fremont, and to the east and south through San Jose to its far-side fringes. Living as I do now in Sunnyvale directly on the Cupertino border, half a mile from both the old Apple hq and its new spaceship, I'm still right in the middle, but that doesn't mean I can get a good cellphone signal at home.