2007 Fast Cities

SAN FRANCISCO, California

Population > 4.2 million

Leading indicator > No. 1 in the world in scientist citations

Fast companies > Lucasfilm; Wild Brain; and nearby, the whole Silicon Valley crowd

Is there a more continuously creative city in the world? The epicenter of U.S. entrepreneurship is still tied to Silicon Valley's fortunes, but it's also hatching its own digital-media sector and a biotech and biomedical hub around UCSF.