SAN Francisco, Silicon Valley and the strip of land that runs along the shore of the Bay between them have had a tremendous decade as the hub of the global technology industry. The area’s biggest companies have soared to heights once unimaginable, coming to represent all that the world finds most exciting about American capitalism. The Valley has revolutionised nearly every aspect of the global economy, transforming how firms make decisions, people make friends and protesters make a fuss.

Silicon rally: How the US technology sector has changed since 1980

Today's tech firms touch more people, more quickly than ever before, partly due to the global increase in smartphone use. As a result, they are growing faster and attracting more money. The figures are eye-watering: Uber, a six-year-old taxi-hailing company, is valued at $41 billion; Airbnb, a seven-year-old firm through which people turn their homes into hotels, is valued at $26 billion. Such success makes it easier to attract wealthy venture capitalists, allowing today's startups to stay private for longer (and avoid regulatory risks). It used to be extremely rare to find a startup valued over $1 billion, but today there are 74 of these so-called “unicorns” in America’s tech sector, valued at $273 billion in total. And as the fortunes of startups have moved upwards, so too have their physical locations. In the 1990s most of the activity was to the south, in areas like Palo Alto and Mountain View, which is still where the area’s big public companies are mostly based (see map). The younger private firms prefer to be much closer to the city itself; Uber, Dropbox, Pinterest and Airbnb all have their headquarters there.