Nathan Masters with a fun bit of trivia:
For decades, then, the Southland was a sort of electrical enclave. Though its borders were unmarked in official atlases, crossing those invisible lines had very real consequences for manufacturers and consumers alike. Some electrical appliances worked at both frequencies, but for frequency-sensitive products manufacturers created special 50hz models just for the Southern California market. And when newcomers moved from outside the region, they paid to have their old devices converted, or simply bought new ones that would work on the 50hz grid.
Much of the U.S. had settled on 60 Hz, but a hydropower plant built in the 1890s set Southern California on a different path.