The local connection: Norton's parents were 1820 Settlers, and he moved to the United States in 1849 from [what is now] South Africa:
At the pre-emptory request of a large majority of the citizens of these United States, I Joshua Norton, formerly of Algoa Bay, Cape of Good Hope, and now for the last nine years and ten months past of San Francisco, California, declare and proclaim myself the Emperor of These United States