Sourdough bread, which originated in ancient Egypt around 1500 BC, was brought to the U.S. by French immigrant Isidore Boudin who founded the Boudin Bakery in San Francisco in 1849, creating the first sourdough French bread in America. The popularity of sourdough surged during the California gold rush, where miners were nicknamed 'sourdoughs' due to their reliance on the bread. Despite the devastation of the 1906 San Francisco earthquake, Boudin's original 'mother dough' was saved, and the bakery continues to uphold the tradition of handcrafting sourdough bread today.