They came by river and by wagon train, braving the endless distances of the Great Plains and the icy passes of the Sierra Nevada. They were men like Linus Rawlings, a restless survivor of Indian country who’d headed east to see the ocean but left his heart—and his home—in the West. They were women like Lilith Prescott, a smart, spirited beauty who fled her family and fell for a gambling man in the midst of a frontier gold boom. These pioneering...