Born in Liverpool into an English-Jewish family, he was a son of Lewis Franklin, a Liverpool banker, and Miriam Abraham. He emigrated from England to San Francisco for the California Gold Rush in October 1849. He was joined by brother Edward and cousins Lewis and Maurice Franklin. Another brother Lumley Franklin arrived in 1854. In 1850 Selim and Edward Franklin ran a zinc-front store on Clay Street Wharf selling mining equipment and supplies. In 1851 they established Selim &amp; Edward Franklin Real Estate and Auctioneers on 77 Battery Street near Long Wharf. Advertisements of properties appeared in The Daily Alta California newspaper. In 1854 they relocated to 102 Merchant Street between Montgomery and Kearny.