(Leinster's  historical model is  the recurring Gold Rush of the Nineteenth Century, drawing adventurers in 1840s from the settled East Coast to wild California, and in 1890s from settled California to the wild Klondike.)
Leinster's historical model is based on the cyclical phenomenon of gold rushes, with individuals migrating from the East Coast in the 1840s to California's wild frontier, and then again from California to the Klondike in the 1890s.